The polychloromethylation/acyloxylation of 1,6-enynes with chloroalkanes and diacyl peroxides through dual-role designs.

The novel polychloromethylation/acyloxylation of 1,6-enynes with chloroalkanes and diacyl peroxides through dual-role designs has been developed to prepare 2-pyrrolidinone derivatives with polychloromethyl units with the use of an inexpensive copper salt under mild conditions. This strategy includes two dual-role designs, not only improving atomic utilization but also allowing a cleaner process. The wide substrate scope and simple reaction conditions demonstrate the practicability of this protocol.

Cyclization/hydrolysis of 1,5-enenitriles initiated by sulfonyl radicals in the aqueous phase in the presence of the I2/TBHP system.

A novel cyclization/hydrolysis of 1,5-enenitriles for the synthesis of valuable pyrrolidine-2,4-diones in the aqueous phase using I2 as the catalyst and tert-butyl hydroperoxide (TBHP) as the oxidant is reported. In the presence of the I2/TBHP system, sulfonyl hydrazides produce sulfonyl radicals, which undergo radical addition, intramolecular cyclization, hydrogen abstraction, and hydrolysis to give the final products. The use of the inexpensive and environmentally friendly I2/TBHP catalytic oxidation system in the aqueous phase makes it a benign and sustainable strategy.

Radical Cyclization of 1,n-Enynes and 1,n-Dienes for the Synthesis of 2-Pyrrolidone.

2-Pyrrolidones have aroused enormous interest as a useful structural moiety in drug discovery; however, not only does their syntheses suffer from low selectivity and yield, but also it requires high catalyst loadings. The radical cyclization of 1,n-enynes and 1,n-dienes has demonstrated to be an attractive method for the synthesis of 2-pyrrolidones due to its mild reaction conditions, fewer steps, higher atom economy, excellent functional group compatibility, and high regioselectivity. Furthermore, radical receptors with unsaturated bonds (i. e. 1,n-enynes and 1,n-dienes) play a crucial role in realizing radical cyclization because of the ability to selectively introduce one or more radical sources. In this review, we discuss representative examples of methods involving the radical cyclization of 1,n-enynes and 1,n-dienes published in the last five years and discuss each prominent reaction design and mechanism, providing favorable tools for the synthesis of valuable 2-pyrrolidone for a variety of applications.