A Cascade Approach to Cyclic Aminonitrones: Reaction Discovery, Mechanism, and Scope
摘要:
Treatment of omega-epoxynitriles with hydroxylamine affords cyclic aminonitrones in a single step and with high stereoselectivity. The scope of this novel transformation was explored in a series of examples. The aminonitrone products were shown to be useful substrates for further selective elaboration.
Free radical additions of hydrogen donor solvents to tert-butyl perpent-4-enoate have given 4-substituted γ-butyrolactones, with yields of 50 % or greater. Such reactions applied to allyl-tert-butyl peroxide have produced 2,3-epoxypropanation of these solvents. Similar addition-elimination processes occurred with tert-butyl 4-methyl-perpent-4-enoate, tert-butyl 2,2-dimethyl-perpent-4-enoate and tert-butyl-methallyl
Sequential treatment of gamma,delta-ketoalkenes with aqueous NBS in DMSO and KOH as solid provides (Z)-cyclopropanes in good overall yields with a diastereoselective excess >99%.
A practical one-pot radical-ionic sequence for the preparation of epoxides: application to the synthesis of unnatural polyhydroxylated alkaloids
An efficient one-pot sequence for the preparation of epoxides from alpha-iodoesters or alpha-iodonitriles and allylic alcohols is described. This sequence is based on the use of iodine atom transfer reaction onto allylic alcohols followed by a ring closing epoxidation reaction of the halohydrin intermediates. The feasibility of this sequence is showcased in the synthesis of the perhydroaza-azulene, an unnatural analog of castanospermine. (C) 2011 Elsevier Ltd. All rights reserved.
Deplacements homolytiques intramoleculaires : V - epoxy-2,3 propanation des acides et derives par thermolyse du peroxyde d'allyle et de t-butyle