An improved two-step synthetic route to allylic alcohols from aldehydes has been developed. A modification of the HWE reaction in H2O–2-PrOH (1 ∶ 1) and a convenient protocol to prepare AlH3 in THF from LiAlH4 and n-BuBr are the key factors in the improvement.
Hg(II) Reagent-Controlled Stereoselective Synthesis of 2,5-<i>cis</i>- and 2,5-<i>trans</i>-Polyhydroxylated Pyrrolidines
作者:Hyunsoo Han、Dinesh Chikkanna
DOI:10.1055/s-2004-832804
日期:——
Stereoselectivity in the intramolecularamidomercuration reaction of 11, which could form 2,5-cis- and 2,5-trans-polyhydroxylated pyrrolidines, was found to be dependent on the nature of the Hg(II) salts used as well as on the stereochemistry and protection state of the hydroxyl group at the allylic carbon. Thus, the amidomercuration reaction of 11 with Hg(CF 3 CO 2 ) 2 led to the predominant formation
A Highly Efficient and Stereoselective
Synthesis of Polyhydroxylated Pyrrolidines via Regioselective
Asymmetric Aminohydroxylation (RAA) and Intramolecular Amidomercuration
Reactions
important polyhydroxylated pyrrolidines 8 and 9, is described. The corner stone of the present strategy is a successful implementation of the regioselective asymmetric aminohydroxylation (RAA) reaction of the designed achiral olefin I and the intramolecular stereoselective amidomercuration reaction of the δ-alkenylamide 4, which were used for the introduction of the vicinal amino alcohol functionality and for
A concise and general methodology for the complete asymmetric synthesis of the orthogonally protected 2-amino-1,3,4-butanetriols (ABTs)
作者:Om V Singh、Hyunsoo Han
DOI:10.1016/s0040-4039(03)01208-5
日期:2003.7
A complete asymmetric synthesis of the orthogonally protected 2-amino-1,3,4-butanetriols I (ABTs: versatile four carbon chiral synthons) was accomplished via the regioselective asymmetric aminohydroxylation (AA) reaction and oxazoline chemistry in four to six steps from the starting olefin 1. The syn-vicinal aminoalcoholfunctionality of I was installed by the regioselective AA reaction of the achiral
Oxazine formation by MsCl/Et3N as a convenient tool for the stereochemical interconversion of the hydroxyl group in N-acetyl 1,3-aminoalcohols. Asymmetric synthesis of N-acetyl l-xylo- and l-arabino-phytosphingosines
作者:Om V. Singh、Dorothy J. Kampf、Hyunsoo Han
DOI:10.1016/j.tetlet.2004.08.030
日期:2004.9
Use of MsCl/Et3N was proven to provide a convenient synthetic tool for the stereochemical intercoversion of the hydroxyl group in N-acetyl 1,3-aminoalcohols. Thus, under these conditions, the alcohols 4 and 6 smoothly converted to the oxazines 5 and 7, respectively, which were hydrolyzed to generate the corresponding inverted alcohols 6 and 4 in one pot. Further elaboration of 4 and 6 led to the efficient asymmetric synthesis of N-acetyl L-xylo- and L-arabino-phytosphingosines (11 and 15), respectively, via olefin cross metathesis reactions. (C) 2004 Published by Elsevier Ltd.