One‐Pot Ring‐Closing Metathesis‐Alkene Cross Metathesis Reactions of Sulfamide‐Linked Enynes

Abstract

Ring-closing metathesis (RCM) of sulfamide-linked enynes 7, 11 and 12 containing disubstituted alkynes afforded a series of novel 7-membered cyclic sulfamides 13−15 in good yield. Substrates 5, 9 and 10 containing mono-substituted alkynes gave either simple RCM products 18a−c or those arising from combinations of enyne RCM and olefin cross metathesis 16/17a−c depending on the reaction conditions. Not-

Controlled Microwave Heating in Modern Organic Synthesis

“…Microwave-assisted enyne-RCM chemistry has been reported by Brown and co-workers. [287] A simple, high-yielding synthesis of 2,4,5-trisubstituted imidazoles from 1,2-diketones and aldehydes in the presence of ammonium acetate was recently reported by Wolkenberg et al [288] Alkyl-, aryl-, and heteroaryl-substituted imidazoles were formed in very high yields ranging from 76-99% by utilizing microwave irradiation. Further microwave-assisted alkylation of 2,4,5-trimethylimidazole with benzyl chloride in the presence of base led to the alkaloid lepidiline B in 43 % overall yield.…”

Green Synthetic Approaches for Medium Ring-Sized Heterocycles of Biological Interest

“…Brown and coworkers developed a highly stereoselective RCM-CM (cross metathesis) sequence between sulfonamide-linked enynes 100 and styrenes (Scheme 17) under MW assistance making the otherwise difficult target compounds 101 accessible [63].…”

Microwave-assisted synthesis of medium-sized heterocycles

“…Brown and co-workers developed a highly selective microwave-assisted one pot RCM-cross metathesis (CM) reaction between sulfonamide linked enynes and styrenes/ acrylates in the presence of a ruthenium carbene complex at 100 1C (Scheme 20). 28 The methodology afforded an efficient access to styryl derivatives of thiodiazepine-1,1-dioxide with a predominant E-configuration.…”