Microwave enabled external carboxymethyl substituents in the ring-closing metathesis
作者:Cangming Yang、William V. Murray、Lawrence J. Wilson
DOI:10.1016/s0040-4039(03)00083-2
日期:2003.2
carboxymethyl substituent is presented. The reaction is enabled through microwave irradiation allowing greatly enhanced yields and conversion rates. The reaction results in the formation of carboxymethyl substituted dihydropyrroles, dihydrofurans, and cyclopentenes. In certain cases, pyrroles are formed through further in situ oxidation.
and mixed copper–zinc reagents) react with β-(allyloxy)-enoates via a radical–polarcrossover process to afford substituted furans in one single synthetic step following a dominoreaction involving Michael addition and carbocyclisation. Reversal of diastereoselectivity can be obtained varying the organometallic and/or the reaction conditions.
Stereoselective synthesis of tetrahydrofurans and tetrahydropyrans by Ni(0) promoted tandem cyclization-carbonylation
作者:Antonio Delgado、Amadeu Llebaria、Francisco Camps、Josep M. Moretó
DOI:10.1016/s0040-4039(00)76727-x
日期:1994.6
Reaction of different vinyl bromides (1a-3a), beating phenyl substituted alkenyloxyalkyl groups, with Ni(CO)4 affords the corresponding substituted cyclic ethers 1b-3b in moderate to good yields and high diastereoselectivity. In the cyclization of 1a, the stereoselectivity of the process can be reversed by the use of additives, such as KOAc, TIOAc, Cs2CO3, and KOCOCF3.