Synthesis of γ,δ-Unsaturated Glycolic Acids via Sequenced Brook and Ireland−Claisen Rearrangements
作者:Daniel C. Schmitt、Jeffrey S. Johnson
DOI:10.1021/ol9029353
日期:2010.3.5
Organozinc, -magnesium, and -lithium nucleophiles initiate a Brook/Ireland−Claisen rearrangement sequence of allylic silyl glyoxylates resulting in the formation of γ,δ-unsaturated α-silyloxy acids.
A Highly Atom Efficient, Solvent Promoted Addition of Tetraallylic, Tetraallenic, and Tetrapropargylic Stannanes to Carbonyl Compounds
作者:Adam McCluskey、I. Wayan Muderawan、Muntari、David J. Young
DOI:10.1021/jo015904x
日期:2001.11.1
Tetraallylic, tetraallenic, and tetrapropargylic stannanes (0.25 equiv) react with aldehydes in methanol to provide unsaturated alcohols in good to excellent yields (56-99%). These reactions proceed exclusively with allylic rearrangement for tetra(2-butenyl)tin 2b and tetra(1,2-butadienyl)tin 16c and predominantly with allylic rearrangement for tetrapropadienyltin 16a and tetra(2-butynyl)tin 6e. Allylation. reactions also proceeded smoothly with reactive ketones such as ethyl pyruvate (9a) and cyclohexanone (9b). The corresponding TFA-catalyzed reactions of dimethyl acetals 4d and 4e are regiospecific with allylic rearrangement.
Diastereo- and enantio-selective crotylation of α-ketoesters using crotyl boronic acid ester complexes
作者:Yanping Chen、Laxman Eltepu、Paul Wentworth
DOI:10.1016/j.tetlet.2004.09.082
日期:2004.11
A diastereo- and enantio-selective crotylation of ethyl pyruvate has been achieved using a chiral boronic acid auxiliary-based approach. This reaction creates two contiguous stereogenic centers, one of which is a quaternary carbon with complete diastereoselectivity and with enantioselectivities up to 7:1 (73% ee). (C) 2004 Published by Elsevier Ltd.