74
Organometallics 1982,1, 74-81
Ph, R’ = H (2.18 mmol) in Nfl-dimethylacetamide (50 mL) instead of benzene. Workup gave 6, R = Ph, R’ = H,in 16% yield. Reaction of 2-Phenylazirinewith 1:l CO/& Catalyzed by Pd(PPhs),. A 1:l carbon monoxide-hydrogen gas mixture was bubbled through a benzene (50mL) solution containing 5,R = Ph, R’ = H (0.531 g, 4.54 mmol), and Pd(PPh3I4(0.58 mmol). Workup in the usual manner (silica gel chromatography)gave 0.15 g (25%) of 6,R = Ph, R‘ = H, and 0.024 g (4.5%) of 4,5diphenylpyrimidine. Reaction of N-m -Butyl-2-phenylaziridine with CO and Pd(PPh3)@The heterocycle (0.602g, 3.44 mmol) and Pd(PPh,), (0.403g, 0.349 mmol) in benzene (50 mL) were stirred under an atmosphere of carbon monoxide at 40 “C for 2 days. Workup gave recovered starting material. Reaction of 4,6-Diphenyl-l,3-diazabicyclo[3.1.O]hex-3-ene (13) with CO and Pd(PPhs),. Starting material was recovered when a mixture of 4,5-diphenyl-l,3-diazabicyclo[3.l.0]hex-3-ene (0.207 g, 0.884 mmol) and Pd(PPh3)4(0.117 g, 0.102 mmol) in benzene (50mL) was exposed to carbon monoxide for 2 days at 40 OC. (Dimethyl acetylenedicarboxylate)bis(triphenylph0sphine)palladium-Catalyzed Carbonylation of 2Phenylazirine (5,R = Ph, R’ = H). A benzene (50 mL) solution of 5, R = Ph, R’ = H (0.510g, 4.36 mmol), and the palladium catalyst (0.337g, 0.436 m o l ) was stirred overnight at 40 O C under a CO atmosphere. Workup gave 0.20 g (35%) of 6,R = Ph, R’ = H. General Procedure for the Pd(dba)2-CatalyzedCarbonylation of Azirines. This reaction was effected in a manner identical with that described for the Pd(PPh3)4reaction, except
for the change in catalyst. The vinyl isocyanate (14)can be isolated by distillati~n’~ of the oil obtained after rotary evaporation. The following procedure was used to obtain pure carbamate ester (15): hexane (20-80 mL) was added to the oil, and the solution was fiitered. Excess (10-20 mL) methanol was added to the filtrate, and the solution was stirred at room temperature for approximately 2 h. After removal of hexane-methanol (rotary evaporation),the residue was chromatographed on silica gel. The product yields are listed in Table 111.
Acknowledgment. We are grateful t o the Natural Sciences and Engineering Research Council for support of this research. We thank Dr. John Krause and Raj Capoor for recording mass and carbon-13 magnetic resonance spectra, respectively. Registry NO.5 (R P-CH~C$I~, R’ = H), 32687-33-5;5 (R = Ph, R’ = H), 7654-06-0; 5 (R = p-Clc&, R’ = H), 32687-35-7;5 (R = p-BrC6H4,R’ = H), 17631-26-4;5 (R = Ph, R’ = CH3),16205-14-4; 6 (R = P-CH~CBH~, R’ = H), 77329-86-3;6 (R = Ph, R’ H), 77329-87-4;6 (R = p-Clc,$14,R’ = H), 77329-88-5; 6 (R = p-BrC6H4, R’ = H), 77329-89-6; 6 (R = Ph, R’ CHS), 77329-90-9;13,3687967-1;14 (R= p-CH&H,, R’ = H), 79152-64-0; 14 (R = Ph, R’ H), 4737-17-1; 14 (R = p-ClC&, R’ = H), 79152-65-1;14 (R p-BrC6H4, R’ = H), 72328-09-7;14 (R = Ph, R’ = CH3), 60995-85-9;15 (R = P-CHSC~H~, R’ = H), 79152-66-2; 15 (R = Ph, R’ = H), 72328-04-2; 15 (R = p-ClC&, R’ = H), 79152-67-3; 15 (R = p-BrC6H4,R’ = H), 72328-10-0;15 (R = Ph, R’ CH3), 79152-68-4; Pd(PPh3),, 1422101-3;Ni(PPh3)4, 15133-82-1;Pt(PPh3)4,14221-02-4;Pd(PPh3)z(COOCH3C4COOCH3),15629-88-6; Pd(dba)z,32005-36-0; Pd(diphos),, 31277-98-2.
Mercury in Organic Chemistry. 22. Carbon-Carbon Bond Formation via Organocopper-Organomercury Cross-Coupling Reactions Richard C. Larock” and Douglas R. Leach Department of Chemistry, Iowa State University, Ames, Iowa 5001 1 Received June 30, 1981
Aryl-, alkenyl-, and alkylmercuriais undergo carbon-carbon bond formation with primary and secondary alkyl- and alkenylcuprate reagents to give fair to excellent yields of cross-coupled products. The reaction tolerates certain functional groups and proceeds stereospecificallywith retention. Mixed diorganocuprates appear to be intermediates in these reactions as evidenced by their ability to add 1,4 to cr,P-unsaturated ketones. Cross-coupling reactions of organometallic reagenta have become an increasingly important tool in the formation of carbon-carbon bonds. Attention has recently focused on the development of mild, new chemo-, regie, and stereoselective organometallic reagents for application in organic synthesis. The ability of organomercurials t o accommodate essentially all important organic functional groups and the ease with which they undergo a variety of mild carbon-carbon bond forming reactions make organomercurials increasingly attractive as synthetic intermediates in organic synthesis. Of late, a variety of synthetically interesting reactions of these compounds have been reported.’ Unfortunately, the direct alkylation of organomercurials is not easily effected. In general, organomercurials are inert toward alkyl halides. Only under forcing condition^^-^ or (1) Larock, R. C.Angew. Chem., Int. Ed. Engl. 1978,17,27-37. (2)KekulB, A.;Franchimont,A. Chem. Ber. 1872,5,906-908.
in the presence of aluminum bromide6 can low to modest yields of cross-coupled products be obtained. We have recently observed that organorhodium(II1) compounds can be employed to effect cross-coupling of alkenyl-, alkynyl-, and arylmercurials and that the reaction can even be carried out by using only catalytic amounts of rhodium (eq l)? However, the catalyst turnover is generally quite low. CH3I
CMh(PPh&
CH3RhI2(PPh3)2
RHgCl
R-CH,
(1)
Bergbreiter and Whitesides have reported that the reaction of primary and secondary alkylmercurials, iodo(tri-n-bu(3)Whitmore, F. C.;Thurman, E. N. J. Am. Chem. SOC. 1929,51, 1491-1503. (4)Schroeder, W.X.;Brewster, R. Q.J. Am. Chem. SOC.1938,60,
751-753.
(5) Gilman, H.; Wright, G. F. J. Am. Chem. SOC.1933,55,3302-3314. (6) Beletakaya, I. P.; Vol’eva, V. B.; Reutov, 0. A. Dokl. Akad. Nauk SSSR 1972,204,9345;Dokl. Chem. (Engl. Traml.) 1972,204,383-385. (7)Larock, R. C.;Hershberger,S. S. Tetrahedron Lett. 1981,2443.
0276-7333/82/2301-0074$01.25/00 1982 American Chemical Society
Organometallics, Vol. 1, No. 1, 1982 75
Mercury in Organic Chemistry
entry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
17 18 19 20 21 22 23
Table I. Methylation of Phenylmercuric Chloridea reaction met h ylcopper re agent added reagents procedure quenching agent LiCuMe, ... A 0, B Pia,; NiCl, FeClZd CuMe ... Li,CuMe, ... A ... B LiCuMe, ... Me1 Li,CuMe, LiCuMe, SSMe, Li,CuMe ,.SMe, LiCuMe,.PBu, LiCuMe,.HMPA LiCu(CN)Me LiCu(SPh)Mef LiCu( C=CCMe,OMe)Me f LiCu( O-t-Bu)Mef
... ... ... ...
A
SMe, SMe, SMe, SMe,
A B A
MeI, 0,
B
0,
A
MeI, 0,
... ... ... ... ... ...
MeI, 0, MeI, 0, 0,
% yield of
tolueneC 45 48 57 60 59 6 60 66 34 55 76 92 65= 52 51 81 92 68 53 31 11 18 28
* Reactions were carried out by adding 0.5 mmol of 1 to 2.5 mmol of methylcopper reagent dissolved in 10 mL of diethyl
ether unless otherwise noted, followed by quenching with methyl iodide and/or oxygen and finally aqueous ammonium Procedure A: reaction maintained at -78 "C for 1 h, warmed to 0 "C for 1 h, and then quenched. B: -78 "C chloride. 0.025-0.05 for 1 h before quenching. Yields were determined by gas chromatography using an internal standard. mmol. e 1.0 mmol of Li,CuMe,. f Reaction run in THF solvent. tylphosphine)copper(I), and tert-butyllithium gives an intermediate of unknown composition that may either be alkylated with methyl iodide or oxidatively coupled with nitrobenzene (eq 2L8 It was concluded that the inter-
7-
R-CH3
R-C(CH,),
mediate is a ternary ate complex containing all three metals and not a simple organocuprate reagent, since conjugate addition to mesityl oxide could not be effected. Unfortunately, arylmercurials could not be cross-coupled with alkyl halides. Alkenylmercurials were not examined. With the recent report that organomercurials undergo a number of radical anion chain reactionsg and the propensity of organocopper reagents to undergo similar reactions,1° we decided to reinvestigate the reactions of organomercurials and organocopper reagents as a potentially valuable new way to alkylate organomercurials. At this time we wish to report that this reaction is quite general in scope, gives fair to excellent yields of cross-coupled products, and takes advantage of the ability of both copper and mercury organometallics to accommodate a variety of organic functionality.
Results and Discussion Alkylation of Arylmercurials. While arylmercurials could not be alkylated by alkyl halides with use of Whitesides' procedure? we have obtained our best yields of cross-coupled products by using these organomercurials. Initially, we chose the reaction of phenylmercuric chloride (8) Berabreiter, D. E.: Whitesidea, G. M.J. Am. Chem. SOC.1974,96, 4937-4944: (9) Ruesell, G. A; Herahberger, J.; Owens, K. J. Am. Chem. SOC.1979, 101, 1312-1313.
(1) and methylcopper reagents as a model system on which to study the effect on the yield of toluene of each of the following reaction variables: oxidizing agents, solvent, temperature, transition-metal salts, methylcopper stoichiometry, methyl iodide addition, ligands, and the use of heterocuprate reagents. The results are summarized in Table I. The oxidation of organocopper-organic halide crosscoupling reactions prior to hydrolysis has been shown to significantly increase the yield of cross-coupled product."J2 The effect of different oxidizing agents was therefore examined on the reaction of 1 and lithium dimethylcuprate (2) (5 equiv). Compound 1 was added to 2 a t -78 "C and maintained a t that temperature for 1 h, before warming to 0 "C (1 h) and either flushing with pure oxygen or adding excess nitrobenzene. Both oxidation procedures gave essentially the same result, a 45% yield of toluene and small amounts of biphenyl (
