Preparation of 2,2-difluoro-1-trialkylsilylethenylstannanes and their cross-coupling reactions
摘要:
Reaction of 2 with bis(tributyltin) in the presence of 3 mol % Pd-2(dba)(3), 6 mol % XPhos, and 30 equiv of LiBr in wet and air bubbled THF at reflux for 8 h afforded the desired products 3 in 73-74% yields. The cross-coupling reaction of 3a with aryl iodides in the presence of 10 mol % Pd(PPh3)(4) and 10 mol % CuI afforded the coupled products 4a-p in 47-90% yields. The coupling reaction of 3h with various alkynyl bromides having aryl-, alkyl, or trialkylsilyl group also afforded the corresponding 1,3-enynes 5a-g in 61-77% yields. (C) 2014 Elsevier Ltd. All rights reserved.
We report a new synthetic sequence for the preparation of silylated 2,2-difluorostyrene derivatives. This new route has numerous advantages over the previous one including enhanced scope, higher yields, ease of purification, and significant reduction of the amount of desilylated side-products. An unexpected transformation of a silylated 2,2-difluorostyrene derivative is also presented.
The cobalt-catalyzed aza-NHK (Nozaki–Hiyama–Kishi) reaction of ketimine has been realized to access diverse α-tertiary vinylic amino esters with excellent enantioselectivity and broad functional group tolerance. Notably, both configuration of alkenyl halide provides the same stereochemical outcome of chiral α-alkenyl quaternary amino ester, indicating that isomerization of alkenyl fragment might be