Mesoporous aluminosilicate-catalyzed allylation of carbonyl compounds and acetals
摘要:
A mesoporous aluminosilicate (Al-MCM-41) was found to be an effective heterogeneous catalyst for the reaction of both carbonyl compounds and acetals with allylsilanes to afford the corresponding homoallyl silyl ethers and homoallyl alkyl ethers, respectively. Both the mesoporous structure and the presence of aluminum moiety were indispensable for the high catalytic activity of Al-MCM-41. Moreover, Al-MCM-41 could catalyze the reaction of acetals chemoselectively in the presence of the corresponding carbonyl compounds. The solid acid catalyst Al-MCM-41 could be recovered easily by filtration and could be reused three times without a significant loss of catalytic activity. (C) 2011 Elsevier Ltd. All rights reserved.
Unusual Carbon−Carbon Bond Formations between Allylboronates and Acetals or Ketals Catalyzed by a Peculiar Indium(I) Lewis Acid
作者:Uwe Schneider、Hai T. Dao、Shu̅ Kobayashi
DOI:10.1021/ol100450s
日期:2010.6.4
mechanism is proposed in which a single InI center acts as a dual catalyst to activate both reagents sequentially. Contrary to the classic γ-selectivity of allylsilanes (Hosomi−Sakuraireaction), this InI-catalyzed boronovariant displays distinct α-selectivity. Substrate scope and functional group tolerance proved to be excellent.
在I OTf中,已发现它是有效的路易斯酸催化剂,用于用烯丙基硼酸酯对乙缩醛或缩酮进行前所未有的亲核取代。提出了一种超金属化S N 1机制,其中单个In I中心充当双重催化剂,以依次激活两种试剂。与烯丙基硅烷的经典γ选择性(Hosomi-Sakurai反应)相反,此In I催化的硼烷变体表现出独特的α选择性。底物范围和官能团耐受性被证明是极好的。
Silicomolybdic acid supported on silica gel: an efficient catalyst for Hosomi–Sakurai reactions
Silicomolybdic acid that is supported on silicagel (50 wt %) efficiently catalyzes the high-yielding Hosomi–Sakurai allylation of carbonyl compounds by allyltrimethylsilane in the presence of benzyl alcohol. The reaction rates of inactive substrates and the yields were greatly increased when preformed acetals were used as substrates.
Trimethysilyl triflate in organic synthesis11Part 11 of this series. Part 10: S. Murata and R. Noyori, Tetrahedron Letters 2107 (1981).
作者:R. Noyori、S. Murata、M. Suzuki
DOI:10.1016/s0040-4020(01)93263-6
日期:——
Trimethylsilyl triflate is a powerful silylating agent for organic compounds and acts as a catalyst which accelerates a variety of nucleophilic reactions in aprotic media. The reactions proceed via one-center, electrophilic coordination of the silyl group to hetero functional groups and exhibit unique selectivities.
A new catalyst trimethylsilyl bis(fluorosulfonyl)imide has been prepared for aldol type reactions and allylation of acetals. The catalyst has been found to be more active than trimethylsilyl triflate for the above reactions.
Trimethylsilyl Trifluoromethanesulfonate Catalyzed One-Pot Method for the Conversion of Aldehydes to Homoallyl Ethers in an Ionic Liquid
作者:Ram Mohan、Peter Anzalone
DOI:10.1055/s-2005-872112
日期:——
A mild method for the trimethylsilyl trifluoromethanesulfonate (TMSOTf) catalyzed one-pot synthesis of homoallyl ethers from aldehydes has been developed in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([bmim] [OTf]). The advantages of this method include the use of a recyclable ionic liquid, facile product isolation without employing excess organic solvent, elimination of an aqueous waste stream, and mild reaction conditions.