A cyanoborohydride‐promoted radicalcyclization methodology has been developed to access α‐chlorolactams in a simple and efficient way using NaBH3CN and trichloroacetamides easily available from allylic and homoallylic secondary amines. This methodology allowed the synthesis of a library of α‐chlorolactams (mono‐ and bicyclic), which were tested for herbicidal activity, trans‐3‐chloro‐4‐methyl‐1‐(
β- and γ-lactams by nickel powder mediated 4-exo or 5-endo radical cyclisations. A concise construction of the mesembrine skeleton
作者:Jérôme Cassayre、Béatrice Quiclet-Sire、Jean-Baptiste Saunier、Samir Z. Zard
DOI:10.1016/s0040-4020(97)10204-6
日期:1998.2
N-Alkenyl trichloroacetamides, upon treatment with nickelpowder and aceticacid in refluxing 2-propanol undergo reversible 4-exo radicalcyclisation. The cyclised radical can be trapped in different ways leading to β-lactams. When the trap is omitted or not efficient enough, unusual irreversible 5-endo cyclisation occurs affording functionalised five-membered lactams. Synthesis of bicyclic γ-lactams
Copper(I) reactions in N-heterocycle synthesis: efficient preparation of substituted pyrrolidinones
作者:David T. Davies、Neha Kapur、Andrew F. Parsons
DOI:10.1016/s0040-4039(99)01805-5
日期:1999.12
Reaction of halo-enamides with copper(I) chloride in boiling toluene has been shown to produce unsaturated pyrrolidinones in excellent yield (81–94%). Both di- and trichloroamide precursors can be used to form dienes via an initial 5-endo-trig radical cyclisation.
Efficient room temperature copper(I) mediated 5-endo radical cyclisations
作者:Andrew J. Clark、Colin P. Dell、John M. Ellard、Nicola A. Hunt、John P. McDonagh
DOI:10.1016/s0040-4039(99)01806-7
日期:1999.12
Reaction of bromo-enamides with catalytic Cu(Me-6-trien)Br at room temperature furnishes regioisomeric mixtures of unsaturated pyrrolidinones in a highly efficient manner via an initial 5-endo radical cyclisation reaction followed by an oxidation and elimination of H+. Bromo-enamide 3f furnishes the beta-lactam via a 4-exo cyclisation pathway. (C) 1999 Elsevier Science Ltd. All rights reserved.