Stereochemistry of transition-metal-catalyzed cross-coupling reactions

Abstract

Acknowledgment. This research was supported in part by the National Institute on Drug Abuse. The help of Mr. Morgan Conrad in obtaining FT IR spectra and Mr. Rudi Nunüst with the UCB-180 NMR spectometer is gratefully acknowledged.

Iron Catalysis in Synthetic Chemistry

“…High selectivity (92% retention of configuration) was obtained when MeLi was used as the transmetalating agent (Scheme 115) (150 Cahiez and co-workers (151) contributed significantly to improve the scope of an iron-catalyzed cross-coupling reaction by utilizing functionalized aryl Grignard reagents and vinyl halides (Table XVIII). Use of N-methylpyridine (NMP) as the solvent additive to THF dramatically increased the yield of the cross-coupled product from 5 to 80%.…”

Enantioselective synthesis of alkylidene cyclohexanes by an asymmetric olefination/cross‐coupling sequence

“…Thereby, the original complex 6 is regenerated to complete the catalytic cycle. Since varying degrees of stereochemical erosion were observed in these types of coupling reactions as well as in the related coupling of bromoalkylidenes to form dissymmetric olefins [28], possible intervention of an electron-transfer-type mechanism cannot be overlooked [29]. Another potential factor for the loss of stereospecificity stems from the deprotonation of (pheny1thio)methylidene 3b by a Grignard reagent to form the corresponding alkenyl anion [25,30].…”

“…In an oven-dried 25 mL, 3-necked, round-bottomed, flask fitted with a glass stopper, reflux condenser topped with a N2-inlet, and septum was placed a suspension of 2b (141.2 + 2 x H,,,,)), 7.17-7.13 (m, 2H, A r (2 x Hortho)), 5.87 ( t , J = 1.6, lH, CHSPh), 3.02-2.97 (m, lH, H,,C(6)), 2.47-2.42 (m, l H , HeqC (2)), 2.18-2.10 (m, lH, H,,C(2)), 1.93-1.79 (m, 3H,HaXC(6), H,,C(3), HeqC (5)), 1.21 (tt,J = 12.0,2.7, lH, HC(4)), 1.11 (dq, J = 12.2, 3.9, lH, HaXC (5)), 1.05 (dq, J = 11.5, 3.9, lH, HaXC (3)), 0.87 (s, 9H, 3 x (C(l')), 128.79 (C(2')), 127.67 (C(3')), 125.41 (C(47), 11 1.45 (CHSPh), 48.01 (C(4)), 36.51 (C(6)), 32.45 (C (7)), 30.25 (C(2)), 28.99 (C(5)), 28.04 (C(3)), 27.59 ((38)); IR (CCI,) ,9.29;S: 12.31. Found: C,78.47;H,9.31;S ,12.24. H3C (8)); "C NMR (100 MHz) 148.03 (C(l)), 137.62 55 (13), 45 (1 l), 43 (12), 42 (38), 40 (10); TLC Rf0.43…”

“…2H,Ha,C(6), H,C (3)), 1.33-1. 18 (m,2H,He@), Ha,C(4)), 1.10-0.97 (m, lH, HaXC (5)), 0.88 (s, 9H, C(CH,),); 13C NMR (100.6 MHz) 144.52 (C(l)), 135.54 (C(l')), 133.53 (C(lO')), 132.35 (C(9')), 128.24 (C(2')), 126.67 (C(4')), 126.60 (C(7')), 125.52 (C(6')), 125.50 (C(5')), 125.29 (C(S')), 125.25 (C(3')), 119.37 (ArCH), 48.23 (C(4)), 37.29 (C(2)), 32.41 (C(CH,),), 29.85 (C(6)), 29.42 (C(3)), 28.66 (C (5) (M+, loo), 221 (14), 193 (13), 180 (24), 179 (57), 178 (261, 167 (21), 166 (18), 165 (62), 154 (30), 153 (161, 152 ( l l ) , 142 (22), 141 (55),57 (60), 55 (lo), 41 (22); TLC R, 0.48 (hexane); [aID_-3.7" (CHCl,, c = 0.57);…”

Recent Progress in Iron Catalyzed C-C Coupling Reactions

“…值得 注意的是, 与二级卤代烃的格氏试剂的反应并没有发现 明显的重排产物. 1981 年, Walborsky [11] 的研究同样证实 了反应具有很高的立体选择性. Molander [12] 则发现卤代 烯烃与大位阻的格氏试剂反应时, 立体选择性会下降 (Scheme 1).…”