Regio- and diastereoselectivity in TiCl4-promoted reduction of 2-aryl-substituted cis-4-methyl-5-trifluoromethyl-1,3-dioxolanes
摘要:
TiCl4-mediated reduction of both syn- and anti-(4S,5S)-2-aryl-4-methyl-5-trifluoromethyl-1,3-dioxolanes with Et3SiD furnished monodeuterated hydroxy ethers resulting from the same regio- and stereoselective C-O bond cleavage (yields >80%; 82-92% de). Deuteride addition to the benzylidene acetal and removal of the alkyl moiety from the reaction product gave (R)-(alpha-H-2)benzy] alcohol (90% ee), thus suggesting a new route to chiral 1-deuteriobenzyl alcohols. A mechanistic rationale is proposed and supported by theoretical calculations. (C) 2002 Elsevier Science Ltd. All rights reserved.
Stereoselective TiCl<sub>4</sub>-Promoted Nucleophilic Substitution at C-2 of (4<i>S</i>,5<i>S</i>)-2-Alkyl-4-methyl-5-trifluoromethyl-1,3-dioxolanes
作者:Carlo F. Morelli、Lavinia Durì、Alberto Saladino、Giovanna Speranza、Paolo Manitto
DOI:10.1055/s-2004-834884
日期:——
ring-opening reactions of chiral acetals derived from (2S,3S)-1,1,1-trifluorobutane-2,3-diol proceed in a completely regioselective manner, leading to the break of the O1-C2 bond accompanied by a high degree of stereoselectivity. The use of triethylsilyl deuteride or allyltributyltin as nucleophiles gives access, after removal of the chiral auxiliary, to stereoselectively deuterated primaryalcohols or homoallylic