3,5-Bis(trifluoromethyl)phenyl Sulfones in the Julia–Kocienski Olefination – Application to the Synthesis of Tri- and Tetrasubstituted Olefins
作者:Diego A. Alonso、Mónica Fuensanta、Carmen Nájera
DOI:10.1002/ejoc.200600478
日期:2006.10
with carbonylcompounds employing phosphazene base P4-tBu at room temp. in THF, affording tri- and tetrasubstituted olefins in good yields. The Julia–Kocienski olefination between primary alkyl BTFP sulfones 8a,b and aromatic and aliphatic ketones affords the corresponding trisubstituted alkenes in good yields and low stereoselectivities. On the other hand, higher yields and stereoselectivities are
Cyclopropylethylenes have been prepared by Wittig reactions, by coupling of dicyclopropylcarbene, and by dehydration of a suitably substituted ethanol. The scope and limitations of these preparations are discussed, particularly with regard to the synthetic application of the Wittig reaction to tetrasubstituted ethylenes.
9,10-Dicyanoathracene-sensitized photoreaction of styrylcyclopropanes in the presence of Cu(BF4)2 in MeCN–MeOH gives α-cyclopropyl nenzyl ketones as major products, which are produced via a two-electron oxidation of styrylcyclopropanes followed by a 1,2-migration of the cyclopropyl group.
Thermal [2 + 2] cycloaddition of cyclopropylethylene with tetracyanoethylene
作者:Shinya Nishida、Ichiro Moritani、Tsutomu Teraji
DOI:10.1021/jo00950a021
日期:1973.5
Aryl and vinyl cyclopropanes through the in situ generation of B-cyclopropyl-9-BBN and its Suzuki–Miyaura coupling
作者:John A. Soderquist、Ramon Huertas、Gisela Leon-Colon
DOI:10.1016/s0040-4039(00)00605-5
日期:2000.6
Dihydroboration of propargyl bromide with 9-BBN-H followed by treatment of the adduct with aqueous sodium hydroxide affords the hydroxy(cyclopropyl)borate complex (1), which undergoes efficient palladium-catalyzed cross-coupling to produce a variety of aryl and vinyl cyclopropanes (2) in good to excellent yields. (C) 2000 Elsevier Science Ltd. All rights reserved.