Cobalt-Catalyzed Regio- and Diastereoselective Formal [3 + 2

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Cobalt-Catalyzed Regio- and Diastereoselective Formal [3+2] Cycloaddition between Cyclopropanols and Allenes Junfeng Yang, Qiao Sun, and Naohiko Yoshikai ACS Catal., Just Accepted Manuscript • DOI: 10.1021/acscatal.8b05114 • Publication Date (Web): 30 Jan 2019 Downloaded from http://pubs.acs.org on January 31, 2019

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ACS Catalysis

Cobalt-Catalyzed Regio- and Diastereoselective Formal [3+2] Cycloaddition between Cyclopropanols and Allenes Junfeng Yang,*† Qiao Sun, and Naohiko Yoshikai* Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore ABSTRACT: A cobalt–diphosphine catalyst has been found to promote a formal [3+2] cycloaddition reaction between a cyclopropanol and an allene via cyclopropanol ring opening, which affords a 3-alkylidenecyclopentanol derivative with high regioand diastereoselectivities. The reaction tolerates monosubstituted, 1,1-disubstituted, and 1,3-disubstituted allenes and various functional groups. The reaction is proposed to proceed through carbometalation of the allene with a cobalt homoenolate followed by intramolecular carbonyl allylation of the resulting allylcobalt species.

KEYWORDS: cobalt catalysis, cycloaddition, cyclopropanes, allenes, homoenolate Substituted cyclopentane scaffolds occur frequently in biologically active natural products and synthetic compounds.1 The (formal) [3+2] cycloaddition via cyclopropane cleavage is among the most frequently pursued approaches for the atomeconomical construction of such five-membered carbocycles,2 with a particular focus on the use of activated cyclopropanes such as donor-acceptor-substituted cyclopropanes3 and methylenecyclopropanes.4 While other functionalized cyclopropanes have also emerged as reactants for [3+2] cycloaddition,5-9 a 1-siloxy(1-alkoxy)cyclopropane has been known to serve as a unique three-carbon unit for a formal [3+2] cycloaddition with an alkynyl ester or amide by way of a stoichiometrically generated zinc homoenolate (Scheme 1a).10,11 Despite its application in the synthesis of various natural products,12 the unsaturated reaction partners for the zinc homoenolate [3+2] cycloaddition have not been extended beyond acetylenic Michael acceptors. Recently, we disclosed cobalt-catalyzed divergent coupling reactions between a cyclopropanol and an internal alkyne to afford a β-alkenyl ketone or a cyclopentenol derivative via a cobalt homoenolate (Scheme 1b).13 In contrast to the zinc homoenolate cycloaddition, the latter [3+2] cycloaddition reaction is notable in that it involves a catalytically generated homoenolate14,15 and engages a nonpolar unactivated alkyne as the coupling partner. Upon further exploration of cyclopropanol transformations using earth-abundant cobalt catalysts, we have developed a formal [3+2] cycloaddition reaction involving allenes as coupling partners, which is reported herein (Scheme 1c). The reaction tolerates monosubstituted, 1,1-disubstituted, and 1,3-disubstituted allenes, and regio- and diastereoselectively affords substituted cyclopentanols, which are relevant to the core structures of various steroids, terpenoids and synthetic pharmaceutical and agrochemical products (see the box in Scheme 1). The present reaction is also notable in that a catalytically active species is generated simply from a cobalt(II) precatalyst and a diphosphine ligand, in light of the necessity of

(organo)metallic reductants in the cyclopropanol/alkyne coupling reactions as well as the majority of C–C bond forming reactions using cobalt–phosphine catalysts.16 Scheme 1. Formal [3+2] Cycloaddition of Homoenolates and Unsaturated Substrates a) Stoichiometric homoenolate– alkynyl ester [3+2] cycloaddition OR2

O OSiMe3

ZnCl2

EtO

O

– Me3SiCl

Zn 2

EtO

+

CuBr•SMe2 HMPA

O

O OR2 R1

R1

b) Our previous work: Chemodivergent & catalytic homoenolate– alkyne coupling O R1

R2 R3

Zn, DABCO DMSO, 80 °C

R2

OH

cat. [Co]

+

R1

R3

cat. [Co]

R1 OH R2

Zn, DABCO MeCN, 80 °C

R3

c) This work: Catalytic homoenolate– allene [3+2] cycloaddition OH R1

R2

R3

+ R4

cat. CoI2– dppm DABCO DMSO, 80 °C

R1 OH R2 R3 • Broad allene scope • Highly regio- and diastereoselective 4 • Reductant-free Co catalyst R N

OH HO

H

H H

O

Ph

N N HO

OH

O H

HO ethinylestradiol

H spathulenol

NMe2 cyclopentolate

Cl metconazole

The present study commenced with exploration of the coupling between 1-phenylcyclopropanol 1a and cyclonona1,2-diene 2a (Table 1; see also Table S1 for more detail). Extensive screening of cobalt precatalysts, ligands, additives, and solvents led to the desired [3+2] cycloaddition in the presence of CoI2 (10 mol %), bis(diphenylphosphino)methane (dppm, 10 mol %), and DABCO (1.5 equiv) in DMSO at 80

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°C, affording the bicyclic cyclopentanol 3a as a single diastereomer in 99% GC yield (89% isolated yield; entry 1).17 It was notable that, unlike the reaction with alkynes (Scheme 1b),13 the present reaction did not require a reductant such as Zn dust.16 Note also that we did not observe an uncyclized hydroalkylation product in the screening experiments. The reaction was found to be highly dependent on the ligand. Thus, the yield of 3a dropped substantially when using other diphosphine ligands such as dppe, dppp, and dppb (entries 2– 4). The use of CoBr2 or CoCl2 instead of CoI2 led to a slightly lower yield of 3a (entries 5 and 6). The amount of DABCO could be reduced to 0.5 equiv without a significant drop in the yield (entry 7), while no reaction was observed in its absence (entry 8). DMSO proved to be the optimal solvent, as the reaction became sluggish in other solvents such as DMF and MeCN (entries 9 and 10). Table 1. Effect of Reaction Conditionsa

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Scheme 2. [3+2] Cycloaddition of Various Cyclopropanols with Allene 2aa

+

R

•

1a– 1q

DABCO (1.5 equiv) DMSO, 80 °C, 12 h 2a

deviation from standard conditions

yield (%)b

1

none

99 (89)

2

dppe instead of dppm

10

3

dppp instead of dppm

35

4

dppb instead of dppm

53

5

CoBr2 instead of CoI2

94

6

CoCl2 instead of CoI2

86

7

DABCO (0.5 equiv)

93

8

DABCO omitted

0

9

DMF instead of DMSO

78

10

MeCN instead of DMSO

27

aThe reaction was performed using 0.15 mmol of 1a and 0.1 mmol of 2a (0.3 M) for 12 h. bDetermined by GC using mesitylene as an internal standard. Isolated yield is shown in the parentheses.

With the optimized Co–dppm catalytic system in hand, we explored the scope of the present [3+2] cycloaddition with respect to cyclopropanols (Scheme 2). A variety of 1arylcyclopropanols bearing electron-donating or electrowithdrawing substituents at the para, meta- or ortho-position participated in the reaction with 2a to afford the corresponding bicyclic cyclopentanols 3aa–3ka in moderate to good yields as single diastereomers. Likewise, 2-naphthyl- and 1-napthylsubstituted cyclopropanols afforded the desired products 3la and 3ma, respectively, in good yields and diastereoselectivity. The reaction also tolerated 2-thienyl-, benzyl- and phenylethyl-substituted cyclopropanols, affording the corresponding products 3na–3pa in moderate yields. The syn configuration of the cyclopentanol ring of 3oa was unambiguously established by X-ray crystallographic analysis.18 Tetrahydronaphthalene-fused cyclopropanol 1q underwent exclusive cleavage of the less substituted C–C bond, and afforded the tetracyclic product 3qa as a single diastereomer in 63 % yield.

3aa– 3qa

R R

OH

OH

OH R

3aa (R = H), 89% 3ba (R = Me), 89% 3ca (R = Cl), 80% 3da (R = Br), 74% 3ea (R = CF3), 73%

3fa (R = OMe), 62% 3ga (R = Cl), 90% 3ha (R = Br), 65% 3ia (R = CF3), 77%

OH

OH

entry

R OH

CoI2 (10 mol %) dppm (10 mol %)

OH

3la, 84%

1q aThe

3na, 64% Ph

3oa, 60%

OH

OH

S

3ma, 76%

OH

Ph

3ja (R = OMe), 83% 3ka (R = F), 77%

X-ray of 3oa

+

2a

std. conditions

OH

3pa, 56%

OH

H 3qa, 63%

reaction was performed on a 0.3 mmol scale.

We next examined the scope of the [3+2] cycloaddition with respect to allenes (Scheme 3). The reaction of cyclopropanol 1a with mono-substituted allenes resulted in selective cycloaddition on the substituted allenic C=C bond, affording the cyclopentanol products 3ab–3aj in moderate to good yields as single diastereomers.19 Substituents such as siloxy (3ae), allyloxy (3af), and hydroxy (3ai) groups were well tolerated, while the reaction of phthalimide-bearing allene was sluggish (see 3ag). It should also be noted that the reaction tolerated allenes substituted with bulky secondary and tertiary alkyl groups (see 3ah–3aj). The cycloaddition of 1a with 1,1dibutylallene also took place on the substituted allenic C=C bond to afford the product 3ak in good yield. 1-Phenyl-1methylallene underwent diastereoselective cycloaddition to afford the product 3al, which features two contiguous tetrasubstituted carbon centers, as a single diastereomer. On the other hand, virtually no diastereoselectivity was observed in the reaction of 1-hexyl-1-methylallene (see 3am). Symmetric 1,3-disubstituted allenes such as nona-4,5-diene also participated in the reaction to afford the product 3an in high yield with E/Z ratio of 5:1. The reaction of unsymmetrical 1-phenyl-3-butylallene afforded the adduct 3ao

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ACS Catalysis arising from cycloaddition on the butyl-substituted C=C bond as the major product (54%), which was accompanied by substantial amount of the regioisomeric products (39%). Besides the reactions using 1a, the fused cyclopropanol 1q also underwent [3+2] cycloaddition with mono-substituted and 1,1-disubstituted allenes to afford the desired tricyclic products in moderate yields as single regio- and diastereoisomers (see 3qb, 3qk, and 3ql). Notably, 3ql derived from 1-phenyl-1-methylallene was found to have anti configuration according to X-ray crystallographic analysis.18 The reaction between 1a and ester-substituted allene 2p furnished the bicyclic lactone product 3ap in moderate yield. Scheme 3. [3+2] Cycloaddition of Various Allenesa R1

OH

CoI2 (10 mol %) dppm (10 mol %)

R2

+

1a or 1q

OH R1 R2

DABCO (1.5 equiv) DMSO, 80 °C, 12 h

R3 2b– 2p

Ph OH

3

Ph OH

Ph OH

n-C6H13

3ab, 91%

Ph

3ac, 76%

aSee the Supporting Information for detailed reaction conditions (unoptimized).

R3

Ph OH

Ph

OTBS

3ad, 65%

3ae, 60%

Ph OH Ph OH

Ph OH

O N

Oallyl O 3af, 78%

3ag, 21%

Ph OH OH

Ph OH OMe

3ai, 77% Ph OH

3ah, 76%

Ph OH

3aj, 48%

3al, 83%

Ph OH

n-Pr

n-C6H13

Ph OH Me Ph

n-Bu n-Bu

3ak, 84%

Ph OH

OH n-C6H13

n-Bu

Me

n-Pr 3an, 91%c

3am, 82%b

n-Bu n-Bu

H

Ph 3ao, 54%d

3qb, 48%

Ph OH Me

OH

H 3qk, 44%

H 3ql, 48%

X-ray of 3ql O

CO2Et OH Ph

as above (72 h)

+

Ph

O H

1a

2p

excellent diastereoselectivity for the epoxidation and hydroboration. In addition, allylic oxidation of 3ab using the SeO2/TBHP system diastereoselectively afforded the cyclopentanediol 8, albeit in a modest yield. Scheme 4. Product Transformationsa

3ap, 53%

aThe

reaction was performed on a 0.3 mmol scale. bdr = 1:1. = 5:1. dA mixture of regioisomeric products was obtained in 39% yield (see the Supporting Information). cE/Z

On the basis of the observed regio- and diastereoselectivities as well as previous reports on allene carbometalation– allylation cascades,20-22 we propose that the present formal [3+2] cycloaddition proceeds through addition of a cobalt homoenolate to the allene and intramolecular addition of the resulting allylcobalt species to the carbonyl group as the regioand diastereocontrolling steps (Scheme 5a). In the presence of DABCO, a (diphosphine)CoII species A and cyclopropanol 1 would form a cobalt(II) cyclopropoxide, followed by ringopening to generate a cobalt(II) homoenolate B. Carbocobaltation of the less substituted allenic C=C bond would take place from the less hindered side via TS1 (where R2 is bulkier than R3),23 generating a nucleophilic allylcobalt intermediate C.24 The intramolecular allylation pathway of C would depend on the allene substituent. For monosubstituted and acyclic 1,3-substituted allenes, allylation would directly take place via a chair-like transition state TS2a,20b where the substituent R4 (in case it is not H) occupies the pseudoequatorial position, and thus end up in the syn configuration of the cyclopentanol and the E-geometry of the C=C bond (Scheme 5b). The reaction of cyclonona-1,2-diene would go through TS2b due to the structural constraint. In contrast to these cases, the anti configuration of 3al and 3ql, derived from 1-phenyl-1-methylallene, would suggest the involvement of a σ-π-σ isomerization process prior to allylation, which would be facilitated by the electronwithdrawing phenyl group (Scheme 5c).25 With such isomerization, allylation would take place through TS2c' rather than TS2c so that unfavorable 1,3-diaxial interaction of the phenyl group could be avoided. Meanwhile, the lack of regioselectivity for 1-hexyl-1-methylallene (3am) might be attributed to poor stereoselectivity in the carbocobaltation step, slow σ-π-σ isomerization, or both. Scheme 5. Proposed Reaction Pathways and Allylation Transition States

The 3-alkylidenecyclopentanol products are amenable to various synthetic transformations (Scheme 4). The exomethylene group of 3ab underwent typical olefin transformations such as epoxidation, hydroboration, cyclopropanation, and ozonolysis to afford the corresponding products 4–7 in moderate to good yields, with good to

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ACS Catalysis (a)

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3

Present Address

1 + base LCoX2

base•HX

† Department

of Chemistry, Fudan University, 2005 Songhu Road, Shanghai 2000438, P.R. China

base•HX

A R1 O[Co] R2 R3

Notes

[Co]

O

The authors declare no competing financial interests.

R1

B

H(R4)

2

ACKNOWLEDGMENT

(H)R4 D [Co]

H

This work was supported by the Ministry of Education (Singapore) and Nanyang Technological University (MOE2016T2-2-043). We thank Dr. Yongxin Li (Nanyang Technological University) for his assistance with the X-ray crystallographic analysis.

R4

R allylation TS

R2

R3

O

[Co]

TS1

H R4

R1

C

R3

O

R=

REFERENCES

R1

R2

(b) R1 OH [Co] O R4

R1

H

R2

H

R2 H

[Co] O H

R4 3ab– 3aj, 3an, 3ao etc.

TS2a

R1 OH R1 H

TS2b

3aa– 3qa

(c) O

[Co]

R1 Me

R1 OH [Co]

O

Me

Ph Me

Ph

Ph

σ-π-σ isomerization

R1

TS2c (disfavored)

O

[Co]

[Co]

R1

Ph

R1 OH O

R1

Ph

Me Ph

Me

Me

TS2c’ (favored)

3al, 3ql

In summary, we have developed a cobalt-catalyzed formal [3+2] cycloaddition reaction between cyclopropanols and allenes via cyclopropanol opening, which regio- and diastereoselectively affords various monocyclic and fused polycyclic 3-alkylidenecyclopentanol derivatives, including those containing contiguous tetrasubstituted carbon centers. The reaction is achieved with a simple and inexpensive catalytic system comprised of cobalt(II) salt, diphosphine ligand, and amine base without need for any reducing agent, and tolerates a wide variety of substituted allenes. Further studies on regio- and stereoselective C–C bond forming reactions using cobalt catalysts26 are currently underway.

ASSOCIATED CONTENT Supporting Information The Supporting Information is available free of charge on the ACS Publications website. Experimental procedures and spectral data for all new compounds (PDF) Crystallographic data for 3oa, 3ql, and 5 (CIF)

AUTHOR INFORMATION Corresponding Author * [email protected] * [email protected]

(1) Heasley, B. Recent Developments in the Stereocontrolled Synthesis of Highly Substituted Cyclopentane Core Structures: From Drug Discovery Research to Natural Product Synthesis. Curr. Org. Chem. 2014, 18, 641-686. (2) De Simone, F.; Waser, J. Cyclization and Cycloaddition Reactions of Cyclopropyl Carbonyls and Imines. Synthesis 2009, 3353-3374. (3) (a) Reissig, H.-U.; Zimmer, R. Donor-Acceptor-Substituted Cyclopropane Derivatives and Their Application in Organic Synthesis. Chem. Rev. 2003, 103, 1151-1196. (b) Yu, M.; Pagenkopf, B. L. Recent Advances in Donor-Acceptor (DA) Cyclopropanes. Tetrahedron 2005, 61, 321-347. (c) Schneider, T. F.; Kaschel, J.; Werz, D. B. A New Golden Age for Donor-Acceptor Cyclopropanes. Angew. Chem., Int. Ed. 2014, 53, 5504-5523. (d) Grover, H. K.; Emmett, M. R.; Kerr, M. A. Carbocycles from Donor-Acceptor Cyclopropanes. Org. Biomol. Chem. 2015, 13, 655-671. (4) (a) Nakamura, E.; Yamago, S. Thermal Reactions of Dipolar Trimethylenemethane Species. Acc. Chem. Res. 2002, 35, 867-877. (b) Nakamura, I.; Yamamoto, Y. Transition Metal-Catalyzed Reactions of Methylenecyclopropanes. Adv. Synth. Catal. 2002, 344, 111-129. (c) Rubin, M.; Rubina, M.; Gevorgyan, V. Transition Metal Chemistry of Cyclopropenes and Cyclopropanes. Chem. Rev. 2007, 107, 3117-3179. (5) For cyclopropyl ketones, see: (a) Lu, Z.; Shen, M.; Yoon, T. P. [3+2] Cycloadditions of Aryl Cyclopropyl Ketones by Visible Light Photocatalysis. J. Am. Chem. Soc. 2011, 133, 1162-1164. (b) Amador, A. G.; Sherbrook, E. M.; Yoon, T. P. Enantioselective Photocatalytic [3+2] Cycloadditions of Aryl Cyclopropyl Ketones. J. Am. Chem. Soc. 2016, 138, 4722-4725. (c) Hao, W.; Harenberg, J. H.; Wu, X.; MacMillan, S. N.; Lin, S. Diastereo- and Enantioselective Formal [3+2] Cycloaddition of Cyclopropyl Ketones and Alkenes via TiCatalyzed Radical Redox Relay. J. Am. Chem. Soc. 2018, 140, 35143517. (d) Huang, X.; Lin, J.; Shen, T.; Harms, K.; Marchini, M.; Ceroni, P.; Meggers, E. Asymmetric [3+2] Photocycloadditions of Cyclopropanes with Alkenes or Alkynes through Visible-Light Excitation of Catalyst-Bound Substrates. Angew. Chem., Int. Ed. 2018, 57, 5454-5458. (6) For nitrocyclopropanes, see: Wang, C.; Ren, X.; Xie, H.; Lu, Z. [3+2] Redox-Neutral Cycloaddition of Nitrocyclopropanes with Styrenes by Visible-Light Photocatalysis. Chem. Eur. J. 2015, 21, 9676-9680. (7) For cyclopropylamines, see: (a) Takemoto, Y.; Yamagata, S.; Furuse, S.; Hayase, H.; Echigo, T.; Iwata, C. CAN-Mediated Tandem 5-exo-Cyclisation of Tertiary Aminocyclopropanes: Novel Accelerative Effect of an N-Benzyl Group for Oxidative RingOpening. Chem. Commun. 1998, 651-652. (b) Maity, S.; Zhu, M.; Shinabery, R. S.; Zheng, N. Intermolecular [3+2] Cycloaddition of Cyclopropylamines with Olefins by Visible-Light Photocatalysis. Angew. Chem., Int. Ed. 2012, 51, 222-226. (c) Nguyen, T. H.; Morris, S. A.; Zheng, N. Intermolecular [3+2] Annulation of Cyclopropylanilines with Alkynes, Enynes, and Diynes via Visible Light Photocatalysis. Adv. Synth. Catal. 2014, 356, 2831-2837. (d) Kuang, Y.; Ning, Y.; Zhu, J.; Wang, Y. Dirhodium(II)-Catalyzed

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ACS Catalysis (3+2) Cycloaddition of the N-Arylaminocyclopropane with Alkene Derivatives. Org. Lett. 2018, 20, 2693-2697. (8) For cyclopropanols, see: Wozniak, L.; Magagnano, G.; Melchiorre, P. Enantioselective Photochemical Organocascade Catalysis. Angew. Chem., Int. Ed. 2018, 57, 1068-1072. (9) For Ni-catalyzed cycloaddition of cyclopropyl ketones, see: (a) Liu, L.; Montgomery, J. Dimerization of Cyclopropyl Ketones and Crossed Reactions of Cyclopropyl Ketones with Enones as an Entry to Five-Membered Rings. J. Am. Chem. Soc. 2006, 128, 5348-5349. (b) Ogoshi, S.; Nagata, M.; Kurosawa, H. Formation of Nickeladihydropyran by Oxidative Addition of Cyclopropyl Ketone. Key Intermediate in Nickel-Catalyzed Cycloaddition. J. Am. Chem. Soc. 2006, 128, 5350-5351. (c) Liu, L.; Montgomery, J. [3+2] Cycloaddition Reactions of Cyclopropyl Imines with Enones. Org. Lett. 2007, 9, 3885-3887. (d) Tamaki, T.; Nagata, M.; Ohashi, M.; Ogoshi, S. Synthesis and Reactivity of Six-Membered OxaNickelacycles: A Ring-Opening Reaction of Cyclopropyl Ketones. Chem. Eur. J. 2009, 15, 10083-10091. (10) (a) Kuwajima, I.; Nakamura, E. Metal Homoenolates from Siloxycyclopropanes. Top. Curr. Chem. 1990, 155, 3-39. (b) Kuwajima, I.; Nakamura, E. In Comprehensive Organic Synthesis; Trost, B., Fleming, I., Eds.; Pergamon: Oxford, 1991; Vol. 2, p 441. (11) (a) Crimmins, M. T.; Nantermet, P. G. Addition of Zinc Homoenolates to Acetylenic Esters: A Formal [3 + 2] Cycloaddition. J. Org. Chem. 1990, 55, 4235-4237. (b) Crimmins, M. T.; Nantermet, P. G.; Trotter, B. W.; Vallin, I. M.; Watson, P. S.; McKerlie, L. A.; Reinhold, T. L.; Cheung, A. W.-H.; Stetson, K. A.; Dedopoulou, D.; Gray, J. L. Addition of Zinc Homoenolates to Acetylenic Esters and Amides: A Formal [3+2] Cycloaddition. J. Org. Chem. 1993, 58, 1038-1047. (12) (a) Crimmins, M. T.; Watson, P. S. Stereoselective Intramolecular Enone-Olefin Photocycloadditions of 1,7-Dienes: Model Studies on the Synthesis of Lycopodium Alkaloids. Tetrahedron Lett. 1993, 34, 199-202. (b) Crimmins, M. T.; Jung, D. K.; Gray, J. L. Synthetic Studies on the Ginkgolides: Total Synthesis of (+/-)-Bilobalide. J. Am. Chem. Soc. 1993, 115, 3146-3155. (c) Crimmins, M. T.; Wang, Z.; McKerlie, L. A. Rearrangement of Cyclobutyl Carbinyl Radicals: Total Synthesis of the Spirovetivane Phytoalexin (+/-)-Lubiminol. Tetrahedron Lett. 1996, 37, 8703-8706. (d) Crimmins, M. T.; Wang, Z.; McKerlie, L. A. Double Diastereoselection in Intramolecular Photocycloadditions: A Radical Rearrangement Approach to the Total Synthesis of the Spirovetivane Phytoalexin (+/-)-Lubiminol. J. Am. Chem. Soc. 1998, 120, 17471756. (e) Crimmins, M. T.; Pace, J. M.; Nantermet, P. G.; KimMeade, A. S.; Thomas, J. B.; Watterson, S. H.; Wagman, A. S. The Total Synthesis of (+/-)-Ginkgolide B. J. Am. Chem. Soc. 2000, 122, 8453-8463. (f) Li, C.-C.; Liang, S.; Zhang, X.-H.; Xie, Z.-X.; Chen, J.-H.; Wu, Y.-D.; Yang, Z. Exploring an Expedient IMDA Reaction Approach to Construct the Guanacastepene Core. Org. Lett. 2005, 7, 3709-3712. (g) Liu, J.; Marsini, M. A.; Bedell, T. A.; Reider, P. J.; Sorensen, E. J. Diastereoselective Syntheses of Substituted cisHydrindanones Featuring Sequential Inter- and Intramolecular Michael Reactions. Tetrahedron 2016, 72, 3713-3717. (13) Yang, J.; Shen, Y.; Lim, Y. J.; Yoshikai, N. Divergent ringopening coupling between cyclopropanols and alkynes under cobalt catalysis. Chem. Sci. 2018, 9, 6928-6934. (14) For selected reviews concerning catalytic transformations of cyclopropanols, see: (a) Marek, I.; Masarwa, A.; Delaye, P. O.; Leibeling, M. Selective Carbon-Carbon Bond Cleavage for the Stereoselective Synthesis of Acyclic Systems. Angew. Chem., Int. Ed. 2015, 54, 414-429. (b) Nikolaev, A.; Orellana, A. Transition-MetalCatalyzed C-C and C-X Bond-Forming Reactions Using Cyclopropanols. Synthesis 2016, 48, 1741-1768. (c) Fumagalli, G.; Stanton, S.; Bower, J. F. Recent Methodologies That Exploit C-C Single-Bond Cleavage of Strained Ring Systems by Transition Metal Complexes. Chem. Rev. 2017, 117, 9404-9432. (15) For more recent examples that are not cited in ref 14, see: (a) Reding, A.; Jones, P. G.; Werz, D. B. Intramolecular transCarbocarbonation of Internal Alkynes by a Cascade of Formal antiCarbopalladation/Cyclopropanol Opening. Org. Lett. 2018, 20, 72667269. (b) Liu, H.; Fu, Z.; Gao, S.; Huang, Y.; Lin, A.; Yao, H.

Palladium-Catalyzed Hydroalkylation of Alkynes with Cyclopropanols: Access to γ,δ-Unsaturated Ketones. Adv. Synth. Catal. 2018, 360, 3171-3175. (c) Wu, P.; Jia, M.; Lin, W.; Ma, S. Matched Coupling of Propargylic Carbonates with Cyclopropanols. Org. Lett. 2018, 20, 554-557. (d) Zhou, X.; Qi, Z.; Yu, S.; Kong, L.; Li, Y.; Tian, W.-F.; Li, X. Synthesis of 2-Substituted Quinolines via Rhodium(III)-Catalyzed C-H Activation of Imidamides and Coupling with Cyclopropanols. Adv. Synth. Catal. 2017, 359, 1620-1625. (e) Davis, D. C.; Walker, K. L.; Hu, C.; Zare, R. N.; Waymouth, R. M.; Dai, M. Catalytic Carbonylative Spirolactonization of Hydroxycyclopropanols. J. Am. Chem. Soc. 2016, 138, 10693-10699. (f) Gyanchander, E.; Ydhyam, S.; Tumma, N.; Belmore, K.; Cha, J. K. Mechanism of Ru(II)-Catalyzed Rearrangements of Allenyl- and Alkynylcyclopropanols to Cyclopentenones. Org. Lett. 2016, 18, 6098-6101. (16) (a) Gosmini, C.; Begouin, J. M.; Moncomble, A. CobaltCatalyzed Cross-Coupling Reactions. Chem. Commun. 2008, 32213233. (b) Hess, W.; Treutwein, J.; Hilt, G. Cobalt-Catalysed CarbonCarbon Bond-Formation Reactions. Synthesis 2008, 3537-3562. (c) Cahiez, G.; Moyeux, A. Cobalt-Catalyzed Cross-Coupling Reactions. Chem. Rev. 2010, 110, 1435-1462. (d) Gao, K.; Yoshikai, N. LowValent Cobalt Catalysis: New Opportunities for C-H Functionalization. Acc. Chem. Res. 2014, 47, 1208-1219. (e) Gandeepan, P.; Cheng, C.-H. Cobalt Catalysis Involving π Components in Organic Synthesis. Acc. Chem. Res. 2015, 48, 11941206. (f) Moselage, M.; Li, J.; Ackermann, L. Cobalt-Catalyzed C-H Activation. ACS Catal. 2016, 6, 498-525. (g) Röse, P.; Hilt, G. Cobalt-Catalysed Bond Formation Reactions; Part 2. Synthesis 2016, 48, 463-492. (17) For 3aa, 3ab, and 3al, minor diastereoisomers were not detected by GC and 1H NMR analysis of the crude products. (18) CCDC 1878942 (3oa), 1878943 (3ql), and 1879319 (5) provide supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre. (19) The syn configuration was assumed for cycloadducts derived from monosubstituted and 1,3-disubstituted allenes on the basis of Xray analysis of 3oa and 5. The product 3al was assumed to have anti configuration in analogy to the established configuration of 3ql. (20) (a) Kuninobu, Y.; Yu, P.; Takai, K. Rhenium-Catalyzed Diastereoselective Synthesis of Aminoindanes via the Insertion of Allenes into a C-H Bond. Org. Lett. 2010, 12, 4274-4276. (b) Tran, D. N.; Cramer, N. syn-Selective Rhodium(I)-Catalyzed Allylations of Ketimines Proceeding through a Directed C-H Activation/Allene Addition Sequence. Angew. Chem., Int. Ed. 2010, 49, 8181-8184. (c) Tran, D. N.; Cramer, N. Enantioselective Rhodium-Catalyzed Dynamic Kinetic Asymmetric Transformation of Racemic Allenes by the [3+2] Annulation of Aryl Ketimines. Angew. Chem., Int. Ed. 2013, 52, 10630-10634. (21) (a) Hopkins, C. D.; Malinakova, H. C. Synthesis of Homoallylic Alcohols via Palladium-Catalyzed Three-Component Coupling of an Arylboronic Acid with Allenes and Aldehydes. Org. Lett. 2004, 6, 2221-2224. (b) Hopkins, C. D.; Guan, L.; Malinakova, H. C. Regiocontrolled, Palladium-Catalyzed Bisfunctionalization of Allenyl Esters. Multicomponent Coupling Approaches to Highly Substituted α,β-Unsaturated δ-Lactones. J. Org. Chem. 2005, 70, 6848-6862. (c) Hopkins, C. D.; Malinakova, H. C. Allylpalladium Umpolung in the Three-Component Coupling Synthesis of Homoallylic Amines. Org. Lett. 2006, 8, 5971-5974. (d) Bai, T.; Ma, S.; Jia, G. Rh(I)-Catalyzed Three-Component Reaction of 2,3Allenoates, Organoboronic Acids, and Aldehydes. An Efficient Synthesis of α,β-Unsaturated δ-Lactones. Tetrahedron 2007, 63, 6210-6215. (22) Chang, H.-T.; Jayanth, T. T.; Cheng, C.-H. Cobalt-Catalyzed Diastereoselective Reductive [3+2] Cycloaddition of Allenes and Enones. J. Am. Chem. Soc. 2007, 129, 4166-4167. (23) Regarding the typical regiochemistry of allene insertion into organometallic species, see the following theoretical studies: (a) Bai, T.; Xue, L.; Xue, P.; Zhu, J.; Sung, H. H.-Y.; Ma, S.; Wiliams, I. D.; Lin, Z.; Jia, G. Organometallics 2008, 27, 2614-2626. (b) Xie, H.; Zhao, L.; Yang, L.; Lei, Q.; Fang, W.; Xiong, C. J. Org. Chem. 2014,

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79, 4517-4527. (c) Xie, H.; Kuang, J.; Wang, L.; Li, Y.; Huang, L.; Fan, T.; Lei, Q.; Fang, W. Organometallics 2017, 36, 3371-3381. (24) (a) Huang, Y.; Ma, C.; Lee, Y. X.; Huang, R.-Z.; Zhao, Y. Cobalt-Catalyzed Allylation of Heterobicyclic Alkenes: LigandInduced Divergent Reactivities. Angew. Chem., Int. Ed. 2015, 54, 13696-13700. (b) Michigami, K.; Mita, T.; Sato, Y. Cobalt-Catalyzed Allylic C(sp3)-H Carboxylation with CO2. J. Am. Chem. Soc. 2017, 139, 6094-6097. (c) Mita, T.; Hanagata, S.; Michigami, K.; Sato, Y. Co-Catalyzed Direct Addition of Allylic C(sp3)-H Bonds to Ketones. Org. Lett. 2017, 19, 5876-5879. (25) For related σ-π-σ isomerization in carbonyl allylation with allyl-transition metal species, see: (a) Zbieg, J. R.; McInturff, E. L.; Leung, J. C.; Krische, M. J. Amplification of AntiDiastereoselectivity via Curtin-Hammett Effects in RutheniumCatalyzed Hydrohydroxyalkylation of 1,1-Disubstituted Allenes: Diastereoselective Formation of All-Carbon Quaternary Centers. J. Am. Chem. Soc. 2011, 133, 1141-1144. (b) Takeda, T.; Yamamoto, M.; Yoshida, S.; Tsubouchi, A. Highly Diastereoselective Construction of Acyclic Systems with Two Adjacent Quaternary Stereocenters by Allylation of Ketones. Angew. Chem., Int. Ed. 2012,

51, 7263-7266. (c) Sam, B.; Luong, T.; Krische, M. J. RutheniumCatalyzed C-C Coupling of Fluorinated Alcohols with Allenes: Dehydrogenation at the Energetic Limit of beta-Hydride Elimination. Angew. Chem., Int. Ed. 2015, 54, 5465-5469. (26) For recent examples from our group, see: (a) Wu, J.; Yoshikai, N. Cobalt-Catalyzed Alkenylzincation of Unfunctionalized Alkynes. Angew. Chem., Int. Ed. 2016, 55, 336-340. (b) Yan, J.; Yoshikai, N. Cobalt-Catalyzed Arylative Cyclization of Acetylenic Esters and Ketones with Arylzinc Reagents through 1,4-Cobalt Migration. ACS Catal. 2016, 6, 3738-3742. (c) Yang, J.; Yoshikai, N. CobaltCatalyzed Annulation of Salicylaldehydes and Alkynes to Form Chromones and 4-Chromanones. Angew. Chem., Int. Ed. 2016, 55, 2870-2874. (d) Yang, J.; Rerat, A.; Lim, Y. J.; Gosmini, C.; Yoshikai, N. Cobalt-Catalyzed Enantio- and Diastereoselective Intramolecular Hydroacylation of Trisubstituted Alkenes. Angew. Chem., Int. Ed. 2017, 56, 2449-2453.

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