Ugi Multicomponent Reaction Followed by an Intramolecular Nucleophilic Substitution: Convergent Multicomponent Synthesis of 1-Sulfonyl 1,4-Diazepan-5-ones and of Their Benzo-Fused Derivatives
A short, two-step approach to the synthesis of diazepane or diazocane systems, based on a Ugi multicomponent reaction followed by a subsequent intramolecular S(N)2 reaction was studied. 1-Sulfonyl tetrahydrobenzo[e]-1,4-diazepin-1-ones 1 were obtained in very high yield through a Ugi multicomponent reaction followed by Mitsunobu cyclization. On the other hand, aliphatic 1-sulfonyl 1,4-diazepan-5-ones 2 could be obtained employing different cyclization conditions (sulfuryl diimidazole). A similar approach toward diazocane rings using hydroxamates as nucleophiles was less successful, affording only O-cyclized adducts or unexpected side products. A mechanistic explanation of the observed outcomes is proposed.
A convergent synthesis of enantiopure bicyclic scaffolds through multicomponent Ugi reaction
An efficient and convergent Ugi synthesis of enantiomerically pure N-acyl-2,5-disubstituted pyrrolidines was coupled with an appropriate secondary transformation to give two series of bicyclic derivatives, namely hexahydro pyrrolo-oxazocinediones and -diazepinediones. (c) 2007 Elsevier Ltd. All rights reserved.