Organometallics 1992,11,1373-1381
1373
Novel Cationic Vinylidene Complexes of Iron( I I)Containing Fe(q-C5H5)L, as Metal Auxiliary (L2 = Bls(dipheny1phosphino)methane (dppm) and Bis(dimethy1phosphino)methane (dmpm)). Crystal Structure of [Fe{=C=C( Me)Ph)(q-C5H5)(dppm) ] I M. Pilar Gamasa, Jose Gimeno," Elena Lastra, and Bianca M. Marth Departamento de Qdmica Organometslica, Facultad de Qdmica, Universmd de Oviedo, 33071 Oviedo, Spain
Adeia Anillo and Antonio Tiripicchio Istituto di Chimica Generale ed Inorganica, UniverSHB di Parma, Centro di Stodio per la Struiturlstlca Diftrattometrica dei CNR, Vkle delle Scienze 78, I43100 Parma, Italy Received July 3 1, 199 1
Electrophilic additions of HBF4.Et20 and MeOS02CF3to the neutral a-alkynyl complexes Fe(C= CR')(q-C5H5)L2yield the cationic vinylidene complexes [Fe{==C=C(R')R2)(q-C5H5)L2]+ (L2 = bis(dipheny1phosphino)methane(dppm), R2 = H, R' = Ph, C02Me,C02Et,tBu, CH20CH3;L2 = dppm, R2 = Me, R' = Ph, tBu, C02Me, CH20CH3;L2 = bis(dimethy1phosphino)methane (dmpm), R2 = Me, R' = CH20CHB,tBu), which have been isolated as tetrafluoroborate or triflate salts in good yields. The reaction with HBF4.Eg0 leads to the cleavage of the C-Si bond to give the of Fe(CdXiMe3)(q-C5H5)(dppm) unsubstituted vinylidene complex [Fe(=C=CHJ (~C&S)(dppm)][BF,]. Methylation of the ethynyl complex Fe(C=CH)(q-C5H5)(dppm) leads to an equilibrium mixture of the corresponding vinylidene complex [Fe(=C=C(R1)R2)(q-C5H5)(dppm)]+ (R' = H, R2 = Me) and the symmetrical analogues (R' = R2 = H; R' = R2 = Me), which are formed by methyl-proton exchange processes. Iodine reacts with Fe(C= CR')(q-C&)(dppm) (R' = Ph, qu), acting as a murce of the electrophiliccation I+,to give the iodovinylidene ) l I= Ph, tBu). 'H, 31P{'H),and '3c NMR data are discussed. complexes [ F e { ~ ( I ) R ' ) ( q - C ~ S ) ( d p p m(R' NMR studies on dppm complexes reveal that the vinylidene unit can readily Variable-temperature31P{1H) rotate at the Fe=C bond; barriers for rotation have been evaluated to be 7.2-9.8 kcal mol-', indicating that there is little steric influence between the relatively bulky phosphine and the vinylidene groups. The structure of [Fe{=C=C(Me)Ph)(q-C,H,)(dppm)]I(2a') has been determined by an X-ray diffraction study. It crystallizes in the monoclinic s ace group P2Jn with 2 = 4 in a unit cell of dimensions a = 19.722 (8) A,b = 15.186 (6)A, c = 11.547(4) and j3 = 102.62 (1)O. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrixleast squares on the basis of 4304 observed reflections to R and R, values of 0.0329 and 0.0436,respectively. In the structure of the cationic complex the Fe atom is almost linearly bonded (FdXl)-C(2)= 173.7 (3)O)to a substituted vinylidene ligand through a short Fe-C(l) bond (1.748(4)A), in agreement with a formal double bond. The coordination around the Fe atom is completed by a q5-bondedcyclopentadienyl group and by two P atoms from a chelating dppm molecule. The orientation of the vinylidene plane is nearly orthogonal to the pseudo mirror plane of the Fe(q-C,H,)(P-P) moiety, in accordance with theoretical predictions and with the negligible steric influence observed in solution.
1,
Introduction Half-sandwich moieties of the type (q5-C5H5)MLL'(M = Fe, Ru; L, L' = CO, phosphines, phosphites) are among the most versatile systems of organotransition-metal chemistry.'" These derivatives have been extensively used in both theoretical and experimental studies, including bonding calculations,48pbconformational analy(1)M = Fe: (a) Johnson, M. D. In Comprehensiue Organometallic Chemistry; Stone, F. G. A., Wilkinson, G., Abel, E. W., Eds.;Pergamon: Oxford, U.K., 1982; Vol. 4,Chapter 31.2. (b) Deeming, A. J. In ref la, Vol. 4,Chapter 31.3. (c) Pearson, A. J. In ref la, Vol. 8, Chapter 58. (d) Koerner von Guetorf, E. A., Grevels, F. W., Fisher, I., Eds. The Organic Chemistry of Iron; Academic Press: New York, 1982;Vol. 1. (e) Cutler, A. R.; Hanna, P. K.; Vites, A. C. Chem. Reo. 1988,88,1363. (2)M = Ru: (a) Bennett, M. A.; Bruce, M. I.; Matheson, T. W. In Comprehensiue Organometallic Chemistry; Stone, F. G. A., Wilkinson, G., Abel, E. W., W.;Pergamon: Word, U.K., 1982;Vol. 4,Chapter 32.3. (b) Albers, M. 0.;Robinson, D. J.; Singleton, G. Coord. Chem. Rev. 1987, 79,l. (c) Seddon, E. A.; Seddon, K. R. The Chemistry of Ruthenium; Elsevier: New York, 1984. (d) Davies, S.G.; McNally, J. P.; Smallridge, A. J. Adu. Organomet. Chem. 1990,30,1. (3)(a) Astruc, D. D. In The Chemistry of the Metal-Carbon Bond; Hartley, F. R., Patai, S., Us.; Wiley: New York, 1987;Vol. 4,p 626. (b) Braterman, P.S., Ed. Reactions of Coordinated Ligands; Plenum Press: London, 1986;Vol. 1.
ses,4c-fkinetics and mechanisms? and synthetic applicat i o n ~ . ' ~ Recent , ~ ~ , ~ remarkable developments6 (M = Fe) (4)(a) Koatic, M. M.; Fenske, R. F. Organometallics 1982,1,974.(b) Schilling,B. E. R.; Hoffmann,R.; Lichtenberger,D. L. J.Am. Chem. SOC. 1979,101,585.(c) Shambayati, S.;Crowe, W. E.; Schreiber, S. L. Angew. Chem., Int. Ed. Engl. 1990,29,256;Angew. Chem. 1990,102,273. (d) Blackbum, B. K.; Davies, S. G.; Sutton, K. H.; Whittaker, M. Chem. SOC. Rev. 1988,17,147.(e) Blackbum, B.K.; Davies, S. G.; Whittaker, M. In Stereochemistry of Organometallic and Inorganic Compounds; Bernal, I., Eds.; Elsevier: Amsterdam, 1988;Vol. 3, Chapter 2. (f) Davies, S.G.; Derome, A. E.; McNally, J. P. J. Am. Chem. SOC.1991,113,2854. (5)For leading references, see for instance: (a) Collman, J. P.; Hegedus, L. S.; Norton, J. R.; Finke, R. G. Principles and Applications of Organotransition Metal Chemistry; University Science Books: Mill Valley, CA, 1987;p 355. (b) Alexander, J. J. In The Chemistry of the Metal-Carbon Bond; Hartley, F. R., Patai, S., Eds.; Wiley: New York, 1985;Vol. 2,p 339. (c) Therien, M. J.; Trogler, W. C. J. Am. Chem. SOC. 1987,109,5127.(d) Brookhart, M.; Buck, R. C. J. Am. Chem. SOC.1989, 111,559. (e) Bryndza, H. E.; Domaille, P. 3.; Paciello, R. A.; Bercaw, J. E. Organometallics 1989,8,379. (6)(a) Hegedus, L. S. In The Chemistry of the Metal-Carbon Bond; Hartley, F. R., Patai, S., Eds.; Wiley: New York, 1985;Vo1.2, p 401. (b) Davies, S.G.; Green, M. L. H.;Mingos, D. M. P. In Reactrons of Coordinated Ligands; Braterman, P. S., Ed.; Plenum Press: London, 1986 Vol. 1,p 897. (c) Reger, D. L. Acc. Chem. Res. 1988,21,229.(d) Davies, S. G. Chem. Br. 1989,268;Aldrichim. Acta 1990,23,31and references therein. (e) Brookhart, M.; Studebaker, W. Chem. Reu. 1987,87,411.(0 Brookhart, M.; Buck, R. C. J. Am. Chem. SOC.1989,111, 559.
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1374 Organometallics, Vol. 11, No. 3, 1992
tion with different alcohols. alkoxvcarbene derivatives have focused on their use in novel synthetic organic methodology as metal auxiliaries for C1 and C2 template ligands, involving highly regio-6a* and stereose1ectivew-' Chsequently, it is now apparent that the reactivity of transformations. the vinylidene group may be controlled by changing the Cyclopentadienyliron derivatives are typical metal auxiliaries in recent metal carbene ~hemistry.~An imancillary ligands and/or the substituents at the fl-carbon. portant class of these well-known complexes is that conHence, the syntheses of new vinylidene complexes would enable us to explore the potential variation in reactivity taining unsaturated carbene groups (cumulenylidenes)E and, in particular, vinylidene units (=C=C(R1)R2),which even if the typea of reactionsdo not change. In this context we believed it of interest to use small-bite diphosphines, have recently received special attention mainly due to their use in a number of stoichiometric organic synthe~es.~ such as bis(diphenylph0sphino)methane (dppm), for which the smaller steric requirements relative to those of dppe Nucleophilic addition dominates the reactivity of vinylor a bis(monodentate phosphine) system could favor the idene complexes, and many nucleophiles can be added reactivity of the vinylidene group. Herein we describe the regioselectively to the extremely electrophilic a-carbon.lo Thus, heterocarbene complexes are obtainedloab*fa by resynthesis and the chemical and structural characterization actions with alcohols, thiols,and amines, whereas additions of an extensive series of novel cationic mono-, di-, and unsubstituted vinylidene complexes [Fe]+=C=C(R1)R2, of nucleophiles such as phosphines and hydride or cyanide isolated as the tetratluoroborate or tdlate salts,where [Fe] anions lead to vinyl derivatives.lh denotes metal auxiliaries of the types Fe(&,H,)(dppm) The synthetic potential of the vinylidene complexes is (complexes la-f, 2a-d, 3a,b) and Fe(tpC5H5)(dmpm) further evident through the possibility of influencing the (dmpm = bis(dimethy1phosphino)methane; complexes reactivity of the bound organic moiety by changing the ancillary ligands (or the metal) in the organometallic 4a,b). auxiliary. Bruce and co-workers'' have wried out studies on the general reaction of alcohols with ruthenium vinylidene complexes and determined that the attack on the a-carbon depends on a combination of electronic factors and the steric constraints imposed by phosphine ligands and the vinylidene substituents. In general, carbonyl ligands, due to their smaller size relative to that of phosphines and their electron-withdrawingcharacter, increase the electrophilicity of the vinylidene a-carbon and hence [Fe]+=C=C(R1)R2; R Ph (dppm), Me (dmpm) the reactivity. In contrast, the presence in the complexes CO2Et (Id), 'eu (le), dppm: $ = H, R' = H (la), Ph (lb), C02Me (IC), of relatively bulky phosphine ligands or disubstituted CH20CH3(If); $ = Me, R' = Ph (21).'eu (2b), C02Me (2c), CH20CH3 vinylidene groups results generally in slower reactions.llbJ2 (Id); F f = I, R' = Ph (3a), ' ~ L I(3b) The information is rather limited for iron vinylidene dmpm: R2 Me, R' = CH20CH3(4r), 'Bu (4b) complexes, but the reactivity seems to be similar. Thus, )]+ = whereas the [ F e { ~ ( R ) M e ) ( l l - C 5 H 6 ) ( d p p e (dppe Only a small number of analogous complexes with bibis(dipheny1phosphino)ethane;R = H, Me) complexes do dentate phosphines have been described. These include not react with methanol,13J4the unsubstituted complex Ph2P(CH2)2PPh2 (dppe) (R' = R2 = H, Me; R' = H, R2 [Fe(=C==CH2)(tpC5H5)(CO)(PPh3)]+ yields, by the reac= Me;lbTb R' = C7H7,R2 = Ph;13" R1 = Ph, R2 = Me, Et, PhCH2;15R' = Me, R2 = CS2Me;16R' = H, R2 = Phl7) and the chiral phosphines Ph2P(CHR),PPh2((S,S)-chiraphoa (7) For leading references see: (a) Brookhart, M.; Liu, Y.; Goldman, E. W.; Timmers, D. A.; Williams, G. D. J. Am. Chem. SOC.1991,113,927 (R = CH3),R' = H, R2 = CsH5, CH,; trans-cypenphos (R and references therein. (b) Brookhart, M.; Liu, Y. J. Am. Chem. SOC. = -(CHJ3-), R' = H, R2 = C$15, Me, V,HJ7). In addition, 1991, 113, 939 and references therein. (c) Guerchais, V.; Lapinte, C.; the pentamethylcyclopentadienylderivative [Fer 2u(4) 0.0329 R 0.0436 Rw N M R R = COzEt (CDCla), 6 14.5 (8, CH3), 43.8 (t, 'Jc-p = 21 Hz, CHZP), 59.6 (8, OCHZ), 77.2 (8, Cp), 113.9 (8, SCp), 127-138 (m, PPh2), 150.4 (t, Jc-p = 37 Hz, CJ, 151.2 (s, CO) ppm; R = CHzOCHS (C&), 6 44.7 (t, 'Jc-p = 20 Hz), 55.6 (9, CH3), 63.1 (8, OCHz), 76.6 (8, Cp), 116.2 (8, =C&, 113.7 (m, CJ, 127.7-140.0 (m, CBH5). (c) Lz= dmpm; R = CHzOCH3,tBu. These complexes were obtained as described above for Lz = dppm. Reaction time, yield (%), color, and IR bands (THF; v(C=C), cm-l), are as follows. R = CHz0CH3: 1 h; 90; red; 2073 (w). Anal. Calcd for C14Hz40PzFe: C, 51.56; H, 7.42. Found: C, 52.05; H, 7.30. R = tBu: 5 h; 60,red-orange; 2068 (w). Anal. Calcd for C1&azFe: C, 56.82; H, 8.34. Found C, 57.25; H, 7.98. 31P(1H)NMR (C.&): R = CHz0CH3,6 22.62 s ppm; R = tBu, 6 22.49 s ppm. lH NMR (CsD6): R = CHz0CH3,6 1.07 (m, PCH3), 1.45 (m, PCH3), 2.30 (m, PCH,), 2.74 (m, PCHJ, 3.51 (s, OCH3),4.13 (t, 3 J p - ~= 1.5 Hz, Cp), 4.65 (m, CHzO); R = tBu, 6 1.12 (m, PCH3), 1.49 (m, PCH3), 1.53 (m, C(CH3)3),2.35 (m,PCH,), 2.80 (m,PCHb),4.11 (5, CP). X-ray Crystal S t r u c t u r e Determination of [Fe(=C=C(Me)Ph(sC5H5)(dppm)]I(2a'). The crystallographic data are summarized in Table V. Unit cell parameters were determined from the 0 values of 30 carefully centered reflections, having 10.9 < 0 < 17.6O. Data were collected a t room temperature, the individual profiles having been analyzed by the method of hhmann and Larsen.n Intensities were corrected for Lorentz and polarization effects, no absorption correction was applied. Only the observed reflections were used in the structure solution and refinement. The structure was solved by Patterson (SHELX-B)~ and Fourier s),~ methods and refbed by full-matrixleast squares ( s H ~ x - ~ first with isotropic and then with anisotropic thermal parameters in the last cycles for all non-hydrogen atoms. All hydrogen atoms were clearly located in the final A F map and refined isotropically. The final cycles of refinement were carried out on the basis of 529 variables; after the last cycles, no parameters (except those of the hydrogen atoms) shifted by more than 1.0 esd. The largest remaining peak (close to the Fe atom) in the fiial difference map was equivalent to about 0.6 e/A3. In the f d cycles of refinement a weighting scheme, w = K/[aZ(F,)+ gF:], was used; at convergence the K and g values were 0.737 and 0.0037, respectively. The atomic scattering factors, corrected for the real and imaginary parts of anomalous dispersion, were taken from ref 29. (27) Lehmann, M. S.; Larsen, F. K. Acta Crystallogr., Sect. A 1974, 30,580. (28) Sheldrick, G. M. SHELX-76 Program for Crystal Structure Determination; University of Cambridge: Cambridge, England, 1976; SHELXS-86Program for the Solution of Crystal Structures; University of GBttingen: Gettingen, FRG, 1986. (29) International Tables for X-Ray Crystallography; Kynoch Press: Birmingham, England, 1974; Vol. IV.
Table VI. Fractional Atomic Coordinates (XlO') and Equivalent Isotropic Thermal Parameters (AzX 10') with Esd's in Parentheses for the Non-Hydrogen Atoms of ComDler 2a I Fe P(1) P(2) C(1) C(2) C(3) C(4) C(5) C(6) C(7) C(8) C(9) C(10) C(11) C(l2) C(13) C(14) C(15) C(16) C(17) C(18) C(19) C(20) C(21) C(22) C(23) C(24) C(25) C(26) C(27) C(28) C(29) C(30) C(31) C(32) C(33) C(34) C(35) C(36) C(37) C(38) C(39)
x/a
Ylb
z/c
2279 (1) 1882 (1) 2218 (1) 1459 (1) 2601 (2) 3113 (2) 3862 (2) 4065 (3) 4760 (3) 5264 (3) 5074 (3) 4383 (3) 2935 (3) 1658 (3) 1042 (2) 1096 (3) 1744 (3) 2089 (3) 2090 (2) 3090 (2) 3378 (2) 4036 (3) 4396 (2) 4120 (3) 3457 (2) 1686 (2) 1254 (3) 870 (4) 917 (3) 1342 (3) 1726 (2) 612 (2) 507 (2) -111 (3) -630 (2) -540 (3) 76 (2) 1503 (2) 1903 (3) 1939 (3) 1592 (3) 1194 (3) 1148 (2)
2200 (1) 3602 (1) 3788 (1) 2495 (1) 2940 (3) 2427 (3) 2658 (3) 3512 (4) 3726 (4) 3091 (5) 2253 (5) 2024 (4) 1571 (3) 3828 (3) 3844 (3) 4536 (3) 4937 (3) 4505 (4) 2630 (3) 4113 (3) 4845 (3) 5121 (3) 4682 (4) 3961 (4) 3667 (3) 4453 (3) 4105 (3) 4661 (5) 5541 (4) 5899 (3) 5359 (3) 2546 (3) 2016 (3) 2038 (4) 2578 (3) 3098 (4) 3078 (3) 1376 (3) 738 (3) -109 (3) -316 (3) 306 (4) 1149 (3)
4881 (1) -783 (1) 1158 (1) 78 (1) -829 (3) -988 (3) -572 (4) -279 (5) 116 (6) 209 (5) -116 (5) -514 (4) -1658 (4) -2636 (4) -2219 (4) -1382 (4) -1269 (4) -2050 (4) 1492 (3) 1867 (3) 1441 (4) 2020 (5) 2986 (5) 3423 (5) 2859 (4) 1927 (3) 2596 (5) 3152 (6) 3071 (5) 2414 (5) 1831 (4) 488 (3) 1402 (4) 1775 (4) 1228 (4) 316 (5) -66 (4) -428 (4) 274 (4) -172 (5) -1293 (6) -1988 (5) -1563 (4)
u,. 51.6 (1) 32.3 (2) 32.6 (3) 31.3 (3) 36.8 (13) 38.2 (13) 43.3 (14) 60.6 (20) 80.1 (26) 82.1 (30) 76.9 (24) 61.0 (21) 55.0 (18) 56.2 (18) 49.9 (16) 49.6 (17) 52.8 (17) 59.3 (19) 35.1 (12) 36.9 (13) 47.3 (14) 58.5 (20) 62.8 (20) 65.6 (21) 48.4 (16) 36.6 (14) 64.3 (21) 95.2 (33) 73.5 (24) 59.4 (19) 46.9 (16) 34.5 (13) 56.4 (19) 62.0 (19) 53.2 (17) 63.0 (21) 50.6 (16) 36.8 (14) 52.2 (17) 64.8 (21) 67.4 (24) 66.3 (20) 53.4 (17)
a Equivalent isotropic U defined as one-third of the trace of the orthogonalized Uij tensor.
All calculations were carried out on the Cray X-MP/12 computer of the "Centro di Calcolo Elettronico Interuniversitario dell'Italia Nord-Orientale" (CINECA, Casalecchio Bologna) and on the Gould Powernode 6040 computer of the "Centro di Studio per la Strutturistica Diffrattometrica" del CNR, Parma, Italy. The final atomic coordinates for the non-hydrogen atoms are given in Table VI. The atomic coordinates and isotropic thermal parameters of the hydrogen atoms are given in Table S1 and the anisotropic thermal parameters for the non-hydrogen atoms in Table 52 (supplementary material).
Acknowledgment: We thank the Direccidn General de Investigacidn Cientifica y T6cnica of Spain for financial support (Proyect PB 87-912) and the Ministerio de Educacidn y Ciencia for a scholarship grant (to E.L.). We are also grateful to Dr. Pablo Bernad (Universidad de Oviedo) for running mass spectra. Registry No, la, 13414826-8; lb, 138813-65-7; IC,138813-67-9; Id, 138813-69-1; le, 138813-71-5; If, 138813-73-7; 2b, 138813-75-9; 2c, 138813-77-1;2d, 138813-79-3;3a, 138813-80-6; 3b, 138813-81-7; 4a, 138834-34-1; 4b, 138834-36-3; [Fe(=C=C(Me)Ph)(rl-C,H,)(dppm)][I], 138813-82-8; Fe(C=CCOzEt)(C0)z(rl-C,H,),
Organometallics 1992,11,1381-1384 130666-28-3;Fe(C=CCH20CH3)(CO)2(rl-CsHs), 138813-83-9; Fe(C=CC02Et)(dppm)(rl-C,H,), 138813-84-0;Fe(C= CCH20CH3)(dppm)(g-C,HS), 138813-85-1; Fe(C= CCH20CH8)(dmpm)(rl-C6HS), 138834-37-4;Fe(C=CtBu)-
1381
[Fe(=C=C(Me)PhJ(rl-CSHs)(dppm)] [Tfl, 138813-87-3.
Supplementary Material Available: Hydrogen atom coordinates and isotropic thermal parameters (Table SI)and an(dmpm)(rl-C6Hs),138834-38-5;Fe(C~CH)(dppm)(rl-C~H5), isotropic thermal parameters for the non-hydrogen atoms (Table 134148-19-9; Fe(~Ph)(dppm)(rl-CSH5), 13414820-2;Fe(C= S2)(2pages); a listhg of observed and calculated structure factors 13414817-7;Fe(C=CtBu)(dppm)(rl(24papea). Ordering information is given on any current masthead CC02Me)(d~~m)(rl-C~~), C&H,),134148188;Fe(C--=CSiMes)(dppm)(rl-CgHs), 134148-16-6; page.
Bismuth( III)Chloride-Aluminum-Promoted Alkylations of Immonium Cations to Amines in Aqueous Media: Unstabilized Carbanion Equivalents for Use in the Presence of Water Alan R. Katritzky,' Navayath Shobana, and Philip A. Harris Center for Heterocyclic Compounds, Depertment of Chemlsby, University of FlorMe, Oalnesvllk, FWhia 326 1 1-2046 Received October 22. 199 1
In the presence of bismuth(1II) chloridemetallic aluminum, allyl, propargyl, benzyl, and methyl halides react with a large range of 1-(aminoalky1)benzotriazolesat room temperature in THF-water to give the in high yields. l-(Amidodcyl)bermtriazolea derived from benzaldehyde corresponding homoalkylated &ea are also succeasfully converted under these conditions into N-substituted amides.
Introduction The Barbier reaction has recently received interest as a one-step alternative to the Grignard reaction, owing to the development of several modifications which expand its synthetic potential. The use of metals alternative to magnesium, such as lithium,' zinc,2bismuth: and lead: has been investigated and ultrasound irradiation has been found to improve yields.5 Generally, intermolecular Barbier reactions are between allyl or benzyl halides and aldehydes or ketones, but the use of other alkyl halides has been reported.2 Recently, electroreductive Barbiertype allylationsof carbonyl compounds have been achieved in metal-redox systems such as Sn(IV)/Sn(0)6 and Bi(III)/Bi(O).' Torii and co-workers have achieved the Barbier allylation of imines using either a TiC&/Al bimetal systemee or alternatively an electroreductive allylation procedure employing a combination of a Pb(II)/Pb(O) redox system and an aluminum anode.8b One of the more intriguing developments concerns the allylation of carbonyl compounds in the presence of water utilizing Organometallics derived from allyl halides and zinc or tin. Such carbon-carbon bond-forming processes involving unstabilized carbanions in aqueous solution are (1)Pearce, P. J.; Richards, D. H.; Scilly, N. F. J . Chem. SOC.,Perkin Trans. 1 1972,1655. (2)Blomberg, C.; Hartog, F. A. Synthesis 1977,18. (3)Wada, M.; Akiba, K. Tetrahedron Lett. 1985,26,4211. (4)Tanaka, H.;Hamatani, T.; Yamashita, S.; Toeii, S. Chem. Lett. 1986,1461. (5)Luche, J.-L.; Damiano, J.-C. J. Am. Chem. SOC.1982,102,7926. (6)Uneyama, K.; Matauda, H.; Torii, S. Tetrahedron Lett. 1984,25, 6017. (7)Minato, M.;Tsuji, J. Chem. Lett. 1988,2049. (8) (a) Tanaka, H.; Inoue, K.; Pokorski, U.; Taniguchi, M.; Torii, S. Tetrahedron Lett. 1990,31,3023.(b) Tanaka, H.; Nakahara, T.; Dhimane, H.; Torii, S. Tetrahedron Lett. 1989,30,4161.
Scheme I
3 R4X
i NR' R2
RSA
5
extremely rare. Allylations of aldehydes were carried out in a variety of two-phase solvent systems. For example, organozinc allylations were performed using aqueous ammonium chloride with either solvent THP or a solid (C-18 silica gel)loas coorganic phase, whereas those of tin were carried out in water-ether or water-THF mixtures and required promotion by traces of acid,ll or aluminum metal." It is likely that the aluminum has two functions; it both generates Sn(0) by reduction of Sn(I1) and Sn(IV) from tin(II) chloride and activates the oxidative addition of allyl bromide to the tin.12J3 Recent developments in aqueous alkylations include organotin alkylations (9)(a) Petrier, C.; Einhorn, J.; Luche, J.-L. Tetrahedron Lett. 1985, 26,1449. (b)Einhorn, C.;Luche, J.-L. J. Organomet. Chem. 1987,322, 177. (c) Petrier, C.;Luche, J.-L. J . Org. Chem. 1985, 50, 910. (10) Wilson, S.; Guazzaroni, M. E. J. Org. Chem. 1989,54,3087. (11)Nokami, J.; Otera, J.; Sudo, T.; Okawara, R. Organometallics 1983. 2. 191. (li)'Uneyama, K.; Kamaki, N.; Moriya, A,; Torii, S. J. Org. Chem. 1985,50,5396. (13)Uneyama, K.;Nanbu, H.; Torii, S. Tetrahedron Lett. 1986,27, 2395.
0276-7333/92/2311-1381$03.00/0 0 1992 American Chemical Society
