Reaction of the lithio-derivative of methoxyallene with hydrazones. Part 1: Synthesis and transformation of α-allenyl hydrazines
作者:Valérie Breuil-Desvergnes、Jacques Goré
DOI:10.1016/s0040-4020(01)00030-8
日期:2001.3
methoxyallene reacts with aldehyde hydrazones leading to expected α-allenyl hydrazines when ether is the solvent of the reaction. The yields are good as well as the diastereoselectivity observed in the case of SAMP-hydrazones. These hydrazines are cleanly transformed to N-dialkylamino-3-methoxy-3-pyrrolines when they are reacted with n-BuLi in THF. These compounds are sometimes accompanied by the isomeric
The asymmetric synthesis of 3-substituted dihydro-2H-isoquinolin-1-ones, dihydro- and tetrahydroisoquinolines is described. The key operation is a tandem 1,2-addition/ring closure sequence employing lithiated ortho-toluamides and aldehyde SAMP-or RAMP-hydrazones as substrates, followed by N-N bond cleavage to remove the auxiliary. Moderate to good yields and high enantiomeric excesses (ee = 85-99%)
描述了 3-取代二氢-2H-异喹啉-1-酮、二氢和四氢异喹啉的不对称合成。关键操作是串联 1,2-加成/闭环序列,使用锂化邻甲苯酰胺和醛 SAMP-或 RAMP-腙作为底物,然后进行 NN 键断裂以去除辅助剂。达到中等至良好的产率和高对映体过量(ee = 85-99%)。
Reaction of the lithio-derivative of methoxyallene with hydrazones. Part 2: Formation of 3-pyrrolines and azetidines; synthetic and mechanistic aspects
作者:Valérie Breuil-Desvergnes、Jacques Goré
DOI:10.1016/s0040-4020(01)00031-x
日期:2001.3
3-pyrrolines when the time and temperature of the reaction are increased, but the rate of this transformation depends on the substituents of the terminal nitrogen. A reaction mechanism is proposed which involves intermolecular or intramolecular electron transfers from the lithium amide leading to hydrazinyl radicals. The relative stabilities of these intermediates may then explain the role of the substituents
Aldimines are transformed into homoallylic amines by treatment with allylic barium reagents in which both the α- and γ-adducts are selectively obtained by simply changing the reaction temperature.