J. Org. Chem. 1984,49, 4322-4324
4322
after chromatographic purification on silica gel. It should be noted that the projection of the isopropyl residue into the presumed pericyclic transition state leading from 3 to 4 seems to offer no impediment to rearrangement. However, cis-terminal substitution on the alkenyl residue prevents rearrangement. For example, substrates 5 and 6 are recovered unchanged after subjection to the rearrangement conditions and subsequent hydrolysis.
5
6
The preparations of the substrate oxapyranones la-f and 3a-e were accomplished by straightforward vinylmetallic 1,2-additions to carbonyls, as exemplified in Scheme I. 0-Alkylation of 4-methyl-1-penten-3-01 (7)1° with the sodium salt of bromoacetic acid gave 8 in 94% yield. Ozonolytic cleavage of the olefin linkage in 8 and Kugelrohr distillation provided the lacto19 (83%) which, when reacted with excess vinylmagnesium bromide in THF at -78 "C, followed by lactonization of the hydroxy acids (camphorsulfonic acid in refluxing benzene), gave la and 3a (70%, 1.53:l). Similarly, reaction of 9 with the Grignard reagent derived from 2-bromopropene followed by acidcatalyzed lactonization gave substrate oxapyranones l b and 3b (58%, 2.54:l). In every case the diastereomeric pairs produced were easily separated by flash chromatography." As illustrated in Scheme I, the keto acid 11, derived from 2-ethoxy-4-methyl-1-penten-3-01(1O),l2 exhibited greater stereoselectivity in the vinyl Grignard addition reactions, providing le and 3e in a 9.61 ratio (56%), and yielding If (51%) free of the corresponding diastereomer.13 The substrates for entries 3 and 9 were prepared by the addition of [trans-/3-(trimethylsilyl)~inyl]lithium~~ to 9. Note that the products of these entries incorporate an allylsilane residue15 for further manipulation. Also illustrated in Scheme I is a sequence by which the trans- or cis-5,6-disubstituted oxapyranones (exemplified by Id and 3d, respectively) can be generated stereoselectively. Addition of the cuprate derived from trans-lpropenyllithium to the aldehyde 12 proceeded with >100:1 Cram-cyclic ~tereoselectivity~~J~ to give the hydroxy ester 13. Acid-catalyzed lactonization gave the lactone Id in very high diastereomeric purity. The epimeric oxapyranone 3d was prepared from 13 by oxidation to the enone and reduction with Zn(BH4)217to provide the hydroxy ester epimer of 13. Acid-catalyzed lactonization proceeded (albeit more sluggishly than for ld) to give the cis-5,g-disubstituted oxapyranone 3d in 95:5 diastereomeric purity.13 (10) 4-Methyl-1-penten-3-01 is commercially available from Wiley Organics, Inc., Columbus, OH. (11) Still, W. C.; Kahn, M.; Mitra, A. J. Org. Chem. 1978, 43, 2923. (12) Prepared by the reaction of (wethoxyviny1)lithium with isobutyraldehyde in T H F a t -78 OC. See: Baldwin, J. W.; Hofle, G. A.; Lever, 0. W., Jr. J. Am. Chem. SOC. 1974,96, 7125. (13) The diastereomer ratios were determined by glass capillary GLC using 25-m columns coated with either SE-54 or Superox-4. (14)(a) Cunico, R. F.; Clayton, F. J. J. Org. Chem. 1976,41,1380. (b) Burke, S. D.; Murtiashaw, C. W.; Dike, M. S.; Strickland, S. M. S.; Saunders, J. 0. Ibid. 1981, 46, 2400. (15) For reviews of allylsilane chemistry, see: (a) Chan, T. H.; Fleming, I. Synthesis 1979,761. (b) Colvin, E. W. 'Silicon in Organic Synthesis"; Butterworths: London, 1981; p 97. (16) Still, W. C.; Schneider, J. A. Tetrahedron Lett. 1980, 21, 1035. (17) (a) Nakata, T.; Tanaka, T.; Oishi, T. Tetrahedron Lett. 1981,22, 4723. (b) McGarvey, G. J.; Kimura, M. J . Org. Chem. 1982, 47, 5420.
Finally, catalytic hydrogenation of the product dihydropyrans proceeds without complication. For example (eq 3), the product 4d is transformed to 14 in good yield,
n::;;zMe EIOH
-
Pd'C
i-PrD
i -Pr
'
~
I
~
(3) z M
14
4d
as shown. A comparison of 14 and the "left-wing'' of the antibiotic X-14547A suggests an application of this method. Reports detailing the use of this versatile method in the synthesis of C-pyranosidic natural products will be forthcoming. Acknowledgment. We gratefully acknowledge the National Institutes of Health for generously supporting this research. High-field NMR spectra were obtained through the NSF Regional NMR Center at the University of South Carolina (CHE 82-07445). Registry No. la, 92420-30-9; lb, 92420-31-0; IC, 92420-32-1; Id, 92420-33-2;le, 92420-34-3; lf, 92420-35-4; 2a, 92420-39-8;2b, 92420-40-1; 2c, 92420-41-2; 2d, 92420-42-3; 2e, 92420-43-4; 2f, 92420-44-5; 3a, 92420-36-5; 3b, 92420-37-6; 3c, 92471-18-6; 3d, 92471-19-7; 3e, 92420-38-7; 4a, 92420-45-6; 4b, 92420-46-7; 4c, 92420-47-8; 4d, 92420-48-9; 4e, 92420-49-0; 7, 4798-45-2; 8, 92420-50-3; 9, 92420-51-4; 10, 92420-53-6; 11, 92420-52-5; 12, 92420-54-7; 13 (epimer l),92456-09-2; 13 (epimer 2), 92420-55-8; 14, 92420-56-9; bromoacetic acid sodium salt, 1068-52-6; vinyl bromide, 593-60-2; 2-bromopropene, 557-93-7; [trans-p-(trimethylsilyl)vinyl]lithium, 55339-31-6.
Steven D. Burke,*' David M. Armistead Frank J. Schoenen Department of Chemistry University of South Carolina Columbia, South Carolina 29208 Received August 27, 1984
Synthesis of Bicyclic Vinylcyclobutanes via Copper(1)-Catalyzed Intramolecular 27r 27r Photocycloadditions of Conjugated Dienes to Alkenes'
+
Summary: Copper(1) trifluoromethanesulfonate catalyzes photobicyclization of myrcene to afford 6,6-dimethyl-2methylenebicyclo[3.2.0]heptane, demonstrating the ability of catalysis to promote novel photochemistry. Sir: We are intrigued by the potential for homogeneous metal catalysis in organic photochemistry2to provide novel and synthetically useful organic reactions. The possibility that vinyl substituents might allow useful transformations of the photoproducts led us to explore the suitability of 1,6-dienes bearing conjugated vinyl substituents as substrates for copper(1)-catalyzed intramolecular 27r + 27r photocycloadditions. We now report that copper(1) trifluoromethane~ulfonate~ (CuOTf) catalyzes a novel intramolecular 27r + 27r photocycloaddition of myrcene ( l ) , affording 6,6-dimethyl-2-methylenebicyclo[3.2.0] heptane (2), a ring system not obtained previously from this triene upon direct4 or triplet sensitized5 ultraviolet irradiation. (1) Copper(1) Catalysis of Olefin Photoreactions. 13. For paper 12 in this series, see: Salomon, R. G.; Ghosh, S.; Raychaudhuri, S. R.; Miranti, T. S. Tetrahedron Lett. 1984, 25, 3167. (2) For a recent review, see: Salomon, R. G. Tetrahedron 1983, 39, 485. (3) Salomon, R. G.; Kochi, J. K. J. Am. Chem. SOC.1973, 95, 1889.
0022-3263/84/1949-4322$01.50/0 0 1984 American Chemical Society
~
J. Org. Chem., Vol. 49, No. 22, 1984 4323
Communications
bonds, as in 10, is preferred over other possible modes of coordination.
Table I. Photoreactions of Myrcene (1)
reaction type triplet sensitizeda direct irradiatedb CuOTf catalyzedC
products, %
4
2
5 75 12 0
22 0
20
6 52 35
2% solution in ether containing 0.03% @-acetonaphthone,Pyrex immersion well; ref 5. 1%solution in hexane or ether, Vycor filter; product distribution from ref 5, conditions from ref 4. 1% solution (0.074 M) in ether containing CuOTf (0.011 M), quartz immersion well: this work.
That similar annulations are possible for construction of 1-vinyl-or 6-vinyl-substituted bicyclo[3.2.0] derivatives was established by successful photocyclization of both 6- and y-vinyl substituted diallyl ethers. Four modes of intramolecular 27r IT photocycloaddition are possible for myrcene (1) to produce vinyl cyclobutanes 2-5. If 1,6-dienes bearing conjugated vinyl
10
Although four modes of intramolecular 2~ + 2 i photo~ cycloaddition are possible for 2-vinyl-substituted 1,6-dienes, the only vinylcyclobutane product detected after irradiation of triene 118 in the presence of CuOTf was l-vinyl-3-oxabicyclo[3.2.0]heptane
+
3
2
1
12
11
Various a-substituted trans,trans-2,4-hexadien-l-ols are readily available from the reaction of trans,trans-2,4hexadien-1-a1with alkyllithiums. The derived allyl 2,4hexadienyl ethers 13a-c (84-88% yields) afford vinylcyclobutanes 14a-c (80-87 %yields)upon irradiation in the presence of C U O T ~Ozonolysis .~ followed by reduction with N&H4 and acetylation afforded epimeric mixtures of the exo and endo cyclobutyl carbinyl acetates 15ax-cx and 15an-cn. The 13b 14b and the 13c 14c cyclizations
-
-
-wMe 'i',
4
\
6
5
substituents undergo copper(1)-catalyzed photocyclization, bicyclo[3.2.0] products are expected on the basis of precedents with simple 1,6-diene~.~For myrcene (l),this prediction is especially interesting since triplet-sensitized irradiation of 1 affords 5 exclusively,5 whereas direct irradiation of 1 affords both 4 and 5 as well as cyclobutene 64 (see Table I). In sharp contrast, we now find that neither 4 nor 5 could be detected among the products formed upon irradiation of 1 in the presence of 15 mol % CuOTf. Instead, an isomeric vinylcyclobutane 2 was produced in addition to the cyclobutene 6 (Table I). The structure of the new product 2 was confirmed by an alternative synthesis. Thus, CuOTf-catalyzed photocyclization of linalool (7) gave 8 which underwent dehy-
13a-c a , R - H ; b,R:Me; C,R:wBu
3. Ac.,Sl%
14a-c
15ax, R :H 85:15 15an, R : H 15bx, R:Me 87:13 15bn, R = M e I ~ c x Rzrr-Bu , 9O:lO 15cn, Rzrr-Bu
are highly stereoselective with respect to the stereochemistry at position 4 in the products.8 The stereochemistry at position 6 is predominately, but not exclusively, exo in the photoproducts 14 and the derived acetates 15. For comparison, the (2)-alkene 168 was prepared and cyclized. Irradiation in the presence of CuOTf afforded a 57:43 mixture of exo and endo epimers 15bx and 15bn, respectively. Since copper(1) catalyzes cis-trans isomerization
-
15bx
7
8
9
dration upon distillation from HMPA. In close analogy with precedent,? a 1:2 mixture of 2 and 9, respectively, was produced. We believe that the unique and predictable structural selectivity of copper(1)-catalyzedintramolecular 27r 27r photocycloaddition is a consequence of two factors. Thus, only C=C bonds coordinated to the copper(1)-catalyst participate in photocycloaddition, and the threeatom-bridged arrangement of parallel chelating C=C
+
(4) (a) Crowley, K. J. Tetrahedron 1965,21,1001. (b) Dauben, W. G.; Cargill, R. L.; Coates, R. M.; Saltiel, J. J.Am. Chem. SOC.1966,88, 2742. (5) Liu, R. S. H.; Hammond, G. S. J. Am. Chem. SOC. 1967,89,4936. (6) (a) Evers, J. Th. M.; Mackor, A. Tetrahedron Lett. 1978,821. (b) Salomon, R. G.; Coughlin, D. J.; Easler, E. M. J.Am. Chem. SOC.1979, 101, 3961. (c) Salomon, R. G.; Coughlin, D. J.; Ghosh, S.; Zagorski, M. G. J. Am. Chem. SOC.1982, 104, 998. (d) Salomon, R. G.; Ghosh, S.; Zagorski,M. G.; Reitz, M. J. Org. Chem. 1982,47,829. (e) Raychaudhuri, S. R.; Ghosh, S.; Salomon, R. G. J. Am. Chem. SOC.1982, 104, 6841. (7) Rosini, G.; Salomoni, A.; Squarcia, F. Synthesis 1979, 942.
+
15bn
57 143
16
of alkenes,1° it is not surprising that photocyclizations of 13 or 16 are not stereospecific. Nevertheless, the potential (8) Details of syntheses and structural characterizations will be presented in a subsequent full account of these studies. (9) Typical procedure: A solution of triene 13b (2.0 g) and (0.20 g) in anhydrous ether was irradiated under nitrogen (CUOT~)~C~H: with a 450-W Hanovia mercury arc through a water-cooled quartz immersion well for 16 h. The resulting solution was washed with ice-cold half-concentrated aqueous NH,OH (50 mL) and saturated aqueous NaCl (50 mL) and dried (MgS04). Solvent was rotary evaporated and the residual oil distilled under reduced pressure to afford 6-( 1-propenyl)4-exo-methyl-3-oxabicyclo[3.2.0]heptane(14b): bp 44 OC (0.45 torr); 'H NMR (CDC1,) 6 1.00 (3 H, d, J = 7 Hz), 1.37-3.13 (8 H), 3.47-4.37 (3 H), 4.97-5.90 (2 H). A sample for analysis was purified further by gasliquid phase chromatography on a in. X 11 f t column of 10% DC 710 Silicone oil on 60/80-mesh Chromosorb P at 120 "C. Anal. Calcd for C10H160:C, 78.90; H, 10.59. Found: C, 78.86; H, 10.46. (10) (a) Nozaki, H.; Nisikawa, Y . ;Kawanisi, M.; Noyori, R. Tetrahedron 1967,23,2173. (b) Whitesides, G. M.; Goe, G. L.; Cope, A. C. J. Am. Chem. SOC.1969,91,2608. (c)Deyrup, J. A.; Betkouski, M. J. Org. Chem. 1972, 37, 3561.
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J. Org. Chem., Vol. 49, No. 22, 1984
utility of triene photocyclization is enhanced by the fact that products such as 15bx or 15cx with four asymmetric centers can be generated stereoselectively from simple acyclic precursors.
Acknowledgment is made to the donors of the Petroleum Research Fund, administered by the American Chemical Society, and to the Naional Science Foundation for support of this research. Registry No. 2, 52475-38-4; 6, 1489-66-3; 7, 78-70-6; 8, 92471-17-5; 9, 52475-37-3; 11, 92397-98-3; 12, 92397-99-4; 13a, 92398-00-0; 13b,92398-01-1; 13c, 92398-02-2;14a, 92398-03-3; 14b, 92398-04-4;14c, 92398-05-5; 15ax, 92398-06-6; 15bx, 92398-07-7; 15cx, 92398-08-8; 15an, 92470-52-5; 15bn, 92470-53-6; 15cn,
Additions and Corrections 92470-54-7;16,92398-09-9;CuOTf, 42152-44-3;myrcene, 123-35-3; 3-oxabicyclo[ 3.2.0]heptan-6-al,92398-10-2; 4-methyl-3-oxabicyclo[3.2.0]heptan-6-a1, 92398-11-3; 4-butyl-3-oxabicyclo[3.2.0]heptan-6-al, 92398-12-4; 3-oxabicyclo[3.2.01heptane-6-methanol, 92398-13-5; 4-methyl-3-oxabicyclo[3.2.0]heptane-6-methanol, 92398-14-6; 4-butyl-3-oxabicyclo[3.2.0]heptane-6-methanol, 92398-15-7. K a m l a k a r Avasthi, S w a d e s h R. R a y c h a u d h u r i Robert G. Salomon* Department of Chemistry
Case Western Reserve University Cleveland, Ohio 44106 Received July 11, 1984
Additions and Corrections Vol. 48, 1983 Richard N.Loeppky* and Witold Tomasik. Stereoelectronic Effects in Tertiary Amine Nitrosation: Nitrosative Cleavage vs. Aryl Ring Nitration. Page 2751. The first author’s name is Loeppky, not Leoppky. Vol. 49. 1984 James C. Barborak* and Jeffrey M. Chance. Direct Synthesis of Ferrocenyl Alcohols from Aldehydes and Ketones.
Page 703, column 1,at top of references. We regret that we overlooked the following important references: (a) Herrmann, R.; Ugi, Ivar Tetrahedron 1981,37, 1001. (b) Misterkiewicz,B. J. Organomet. Chem. 1982,224,43.
K. Michal Pietrusiewicz,* Maria Zablocka, and Jaroslaw Monkiewicz. Optically Active Phosphine Oxides. 2. Novel Approach to Enantiomeric Dialkylphenylphosphine Oxides. Page 1522. Abstract, line 2. The Sp configuration in (-)(Sp)-ethyl((menthoxycarbony1)methyl)phenylphosphineshould read Rp.
