Enantioselective Palladium-Catalyzed Alkenylation of Trisubstituted Alkenols To Form Allylic Quaternary Centers
作者:Harshkumar H. Patel、Matthew S. Sigman
DOI:10.1021/jacs.6b09649
日期:2016.11.2
In this report, we describe the generation of remote allylic quaternary stereocenters β, γ, and δ relative to a carbonyl in high enantioselectivity. We utilize a redox-relay Heck reaction between alkenyl triflates and acyclic trisubstituted alkenols of varying chain-lengths. A wide array of terminal (E)-alkenyl triflates are suitable for this process. The utility of this functionalization is validated
Catalytic Chemo-, Regio-, and Enantioselective Bromochlorination of Allylic Alcohols
作者:Dennis X. Hu、Frederick J. Seidl、Cyril Bucher、Noah Z. Burns
DOI:10.1021/jacs.5b01384
日期:2015.3.25
Herein we describe a highly chemo-, regio-, and enantioselective bromochlorination reaction of allylic alcohols, employing readily available halogen sources and a simple Schiff base as the chiral catalyst. The application of this interhalogenation reaction to a variety of substrates, the rapid enantioselectivesynthesis of a bromochlorinated natural product, and preliminary extension of this chemistry to
Selectivity in the cycloadditions of carbonyl ylides with glyoxylates: an approach to the zaragozic acids—squalestatins
作者:David M. Hodgson、James M. Bailey、Carolina Villalonga-Barber、Michael G. B. Drew、Timothy Harrison
DOI:10.1039/b004870o
日期:——
Reaction of diazodiketoester 8 with glyoxylates in the presence of catalytic rhodium(II) acetate generates 6,8-dioxabicyclo[3.2.1]octanes 9 and 11 in good yield. Elaboration of 9 provides a suitable alcohol 25 for acid-catalysed rearrangement to give the 2,8-dioxabicyclo[3.2.1]octane skeleton 26 of the zaragozic acidsâsqualestatins. More substituted diazodiketoesters 36 and 40 also undergo highly regio- and diastereoselective cycloaddition with glyoxylates to give the cycloadducts 41, 43 and 44.
Ruthenium-catalysed reductive cleavage reactions of allylic carboxylates and carbonates with formic acid and triethylamine to give olefins were explored. As an application of the ruthenium-catalysed processes, a new synthetic route to α-hydroxy acids has been discovered. The reductive cleavage of allylic esters is considered to proceed through π-allylruthenium intermediates.
A cycloaddition-rearrangement approach to the squalestatins
作者:David M. Hodgson、James M. Bailey、Timothy Harrison
DOI:10.1016/0040-4039(96)00893-3
日期:1996.6
Reaction of diazodiketoester 4 with methyl glyoxylate in toluene in the presence of catalytic rhodium(II) acetate generates the 6,8-dioxabicyclo[3.2.1]octane 5 as a single regio- and stereo-isomer in good yield. Elaboration provides a suitable alcohol 7 for acid-catalysed rearrangement to give the 2,8-dioxabicyclo[3.2.1]octane skeleton 8 of the squalestatins.