We used dimethylzinc to develop a conjugate addition reaction of imidomethyl radicals to alkylidenemalonates, in which we observed a significant differencebetween succinimidomethyl and phthalimidomethyl radicals. This reaction provides new access to γ-aminobutyric acid derivatives, which often function as neurotransmitters.
Alpha-Halogenoalkyl carboxylates (FG-R1CH(X)(OCOR2); FG = COOR, CN, SR; X = I, Br) were readily prepared by the addition of an acid chloride or bromide (R2COX; X = Br or Cl) to an aldehyde (FG-RCHO) in the presence of a catalytic amount of ZnCl2. They insert efficiently zinc dust in THF-DMSO (X = Br, 8-10-degrees-C, 6-10 h) affording the corresponding zinc organometallics at the a position to oxygen FG-RCH(ZnBr)(OAc). After the addition of the THF-soluble copper salt CuCN.2LiCl, the corresponding copper reagents FG-RCH(Cu(CN)ZnBr)(OAc) are formed and reacted with various classes of electrophiles such as acid chlorides, aldehydes, enones, allylic and alkynyl halides, activated alkynes, nitro olefins and alkylidenemalonates providing polyfunctional molecules in excellent yields. Similarly, zinc organometallics at the a position to the nitrogen of cyclic imides were prepared by the zinc insertion to cyclic alpha-chloromethyl (or alpha-chloroethyl) imides. After their transmetalation to the corresponding copper organometallic ((R1CO)2NCH(R)(Cu(CN)ZnCl); R = Me or H), they were reacted with allylic and alkynyl halides and ethyl propiolate affording polyfunctional imides. The reaction of cyclic N-(chloromethyl)imides with aldehydes in the presence of chromium(II) chloride in THF furnishes protected amino alcohols in 36-95% yield.
Orlova, N. A.; Shipov, A. G.; Baukov, Yu. I., Journal of general chemistry of the USSR, 1984, vol. 54, # 6, p. 1281 - 1282
作者:Orlova, N. A.、Shipov, A. G.、Baukov, Yu. I.
DOI:——
日期:——
Knochel Paul, Chou Tso-Sheng, Jubert Carole, Rajagopal Duddu, J. Org. Chem., 58 (1993) N 3, S 588-599