Reduction of monothioacetals with SmI2: application to [2,3]-Wittig rearrangement
摘要:
Simple reduction of ,S-acetals with SmI2 yielding ethers with selective liberation of the sulfenyl group can be accomplished using benzene-HMPA with t-BuOH. When O,S-acetals possess an O-allyl group, the [2,3]-Wittig rearrangement yielding homoallyl alcohols follows the elimination of a sulfenyl group. For chemoselective elimination of an alkoxy group to give sulfides, MeOTf serves as a moderately effective additive. (C) 2001 Elsevier Science Ltd. All rights reserved.
Catalytic asymmetric allylation of aldehydes with allylic trialkylstannanes was achieved with BINAP•AgOTf complex as catalyst. The chiral silver(I) catalyst was readily prepared by stirring an equimolar mixture of BINAP and silver(I) triflate in THF at room temperature. The allylation of a variety of aromatic and α,β-unsaturated aldehydes resulted in high yields and remarkable enantioselectivities
Highly reactive metals from potassium—graphite. Preparation and use of titanium—graphite and tin—graphite
作者:Gian Paolo Boldrini、Diego Savoia、Emilio Tagliavini、Claudio Trombini、Achille Umani-Ronchi
DOI:10.1016/0022-328x(85)88107-9
日期:1985.2
The potassium—graphite route to active forms of metals has been extended to the preparation of titanium—graphite (TiGr) and tin—graphite (SnGr). The TiGr is used to achieve the reductive coupling of ketones to give alkenes, and SnGr is used in the preparation of diallyltin dibromide complexes which react with aldehydes to give homoallylic alcohols.
Homoallylic (but-3-enylic) alcohols have been prepared in good yields
by reductive allylation of aldehydes in water with various allylic
chlorides in the presence of tin(II) chloride and potassium
iodide. The Barbier type reaction with prop-2-ynyl chloride is also
achieved under the same conditions.
Stannyl-oriented regioselective allylation and its application to the synthesis of silyl misoprostol
作者:Adam Shih-Yuan Lee、Chen-Wen Wu
DOI:10.1016/s0040-4020(99)00743-7
日期:1999.10
mixture of Zn, CeCl3, 3-bromo-1-tributylstannylpropene and aldehyde or ketone in THF/PhH ( was sonicated in a commercial cleaning bath. δ-Tributylstannylhomoallyl alcohol was produced as the sole regioselective product and (E)-stereoisomer was formed as major adduct. Silyl Misoprostol was synthesized by the coupling reaction of cyclopentenone and stannylhomoallyl alcohol.