Reagents Gilman

Organocopper compounds used for carbon-carbon bond formation are called Gilman reagents in honor of Henry Gilman who first stud led them Gilman s career in teaching and research at Iowa State spanned more than half a century (1919-1975)... 

Gilman reagent (Section 10.8) A diorganocopper reagent, R2CUU. 

Coniine, molecular model of. 28 structure of, 294 Conjugate acid, 49 Conjugate base, 49 Conjugate carbonyl addition reaction, 725-729 amines and, 727 enamines and, 897-898 Gilman reagents and, 728-729 mechanism of, 725-726 Michael reactions and, 894-895 water and. 727 Conjugated diene, 482... 

The sense of the asymmetric induction at the /J-carbon of 10 is opposite to that of 7, indicating that 10 reacts with the Gilman reagents in a conformation where the carbonyl is s-trans to the a,(i double bond to avoid steric repulsion of the a-substituent and the camphor residue. 

See Stemmier, T.L. Barnhart, T.M. Penner-Hahn, J.E. Tucker, C.E. Knochel, P. Bohme, M. Frenklng, G. J. Am. Chem. Soc., 1995, 117, 12489 for a discussion concerning the structure of organocuprate reagents. Solution compositions of Gilman reagents have also been studied. See Lipshutz, B.H. Kayser, F. Siegmann, K. Tetrahedron Lett., 1993, 34, 6693. 

Allenic amino acid derivatives 50, which are of special interest as selective vitamin Bg decarboxylase inhibitors [35], are accessible through 1,6-cuprate addition to 2-amino-substituted enynes 49 (Eq. 4.22) [36]. Because of the low reactivity of these Michael acceptors, however, the reaction succeeds only with the most reactive cuprate the t-butyl cyano-Gilman reagent tBu2CuLi-LiCN. Nevertheless, the addition products are obtained with good chemical yields, and selective deprotection of either the ester or the amino functionality under acidic conditions provides the desired target molecules. 

Highly enantioselective 1,5-substitution reactions of enyne acetates are also possible under carefully controlled conditions (Eq. 4.31) [46]. For example, treatment of enantiomerically pure substrate 70 with the cyano-Gilman reagent tBu2CuLi-LiCN at —90 °C provided vinylallene 71 as a 1 3 mixture of E and 2 isomers with 20% and 74% ee, respectively. This mediocre selectivity might be attributable to race-mization of the allene by the cuprate or other reactive copper species formed in the reaction mixture. The use of phosphines as additives, however, can effectively prevent such racemizations (which probably occur by one-electron transfer steps) [47]. Indeed, vinylallene 71 was obtained with an ee of 92% for the E isomer and of 93% for the 2 isomer if the substitution was performed at —80 °C in the presence of 4 eq. of nBusP. Use of this method enabled various substituted vinylallenes (which are interesting substrates for subsequent Diels-Alder reactions Sect. 4.2.2) to be prepared with >90% ee. 

---