A Gold-Catalyzed Entry into the Sesquisabinene and Sesquithujene Families of Terpenoids and Formal Total Syntheses of Cedrene and Cedrol
作者:Alois Fürstner、Andreas Schlecker
DOI:10.1002/chem.200801382
日期:2008.10.20
into the bicyclic cyclopropyl ketone derivatives 5 and 6 by way of a gold-catalyzed Ohloff-Rautenstrauch-type enynecycloisomerization is described. The required substrates were prepared by an asymmetric addition of the branched allylzinc reagent 21 to the alkynyl aldehyde 17 mediated by the deprotonated bisoxazoline (BOX) ligand 22. Compounds 5 and 6 were then converted into a host of different members
Catalytic enantioselective allylboration of propargylic aldehydes
作者:Urmibhusan Bhakta、Erin Sullivan、Dennis G. Hall
DOI:10.1016/j.tet.2013.11.095
日期:2014.1
Homoallylic propargylicalcohols are important building blocks in natural product synthesis. This moiety can be transformed into various other structures by performing other known transformations, which can in turn lead to the synthesis of biologically useful compounds. Herein, a methodology based on Lewisacid assisted Brønstedacid catalysed allylboration of propargylic aldehydes is described. A
Stereocontrolled Synthesis of a C<i><sup>n</sup></i>-C<i><sup>n</sup></i><sup>+7</sup>Building Block (“Eastern Moiety”) for the Unnatural Enantiomers of Important Polyol,Polyene Antibiotics Based on a Ring-Closing Metathesis and an Aldol Addition of a Lactone Enolate
作者:Sonja B. Kamptmann、Reinhard Brückner
DOI:10.1002/ejoc.201300183
日期:2013.10
A stereocontrolledsynthesis of epoxide 6, which represents the Cn–Cn+7 or “eastern moiety” building block for the title compounds, has been realized in 19 steps. Our synthesis started from tetrabromoacetone 26 and afforded dibromotriene 33b in six steps. The latter was subjected to a ring-closing metathesis, which gave the dibromovinyl-substituted lactone 34 in high yield. A highly stereoselective
Convergent Synthesis of Fostriecin via Selective Alkene Couplings and Regioselective Asymmetric Dihydroxylation
作者:Omar Robles、Frank E. McDonald
DOI:10.1021/ol902365n
日期:2009.12.3
synthesis of fostriecin is described, featuring sequential palladium-catalyzed Negishi cross couplings to form the C7−C8 bond and C8−methyl bond, followed by late-stage regio- and stereoselective dihydroxylation of C8−C9.
inherently flexible approach opened access to nannocystin Ax (1) itself as well as to 10 non-natural analogues. While the biological data confirmed the remarkable potency of this class of compounds and showed that the domain in question is indeed an innate part of the pharmacophore, the specific structure/activity relationships can only partly be reconciled with the original in silico docking study; therefore