The current state-of-the-art synthesis for the formation of enantiomerically enriched all-carbon quaternary stereocenters in acyclic system relies on the formation of a single carbon-carbon bond per chemical step by asymmetric catalysis. These extraordinary sophisticated methods were logically classified among the most powerful and innovative ones. In this concept article, we are proposing a new retrosynthetic
Synthèse stéréospécifique récurrente de structures apparentées à celle de l'hormone juvénile de Hyalophora cecropia
作者:C. Chuit、G. Cahiez、J. Normant、J. Villieras
DOI:10.1016/0040-4020(76)85157-5
日期:1976.1
A stereospecific synthesis of Hyalophoracecropiajuvenilehormone analogs is proposed. The three double bonds are obtained successively by addition of an alkyl copper reagent to the apporpriate 1-alkyne.
Carbocupration/Zinc Carbenoid Homologation and β-Elimination Reactions for a New Synthesis of Allenes − Application to the Enantioselective Synthesis of Chiral Allenes by Deracemization of sp3-Organometallic Derivatives
作者:Jos P. Varghese、Irena Zouev、Lionel Aufauvre、Paul Knochel、Ilan Marek
straightforward carbocupration/zinc homologation/β-elimination reaction sequence allows the one-pot synthesis of polysubstituted allenes from acetylenic sulfoxides in excellent isolated chemical yields. Secondary zinccarbenoids were used for the homologation reaction, and so a new synthesis of 1,1-diiodoalkanes is described. This methodology also allows the synthesis of chiral allenes through thermodynamic
Aminosilanes in organic synthesis. addition of organocopper reagents on γ-bis(trimethylsilyl)amino-α-acetylenic amides, esters and ketones. stereochemistry and some synthetic uses.
The stereochemical outcome of the carbocupration of γ-bis(trimethylsilyl)amino-α-acetylenic amide, esters and ketone was studied. A judicious choice of substrate, reagent and(or) reaction conditions allows to perform highly stereoselective cis or trans addition. The intermediate vinylic copper adducts, with (E) or (Z) configuration, react with electrophilic reagents to provide short routes to substituted
Allenyl-germanes and -stannanes, Ph3MC(R)CCR′R″ (M = Ge, Sn) can be obtained, generally in excellent yield, through alkylcopper(I)-induced 1,3-substitution of the propargylic chlorides Ph3MCCCR′R″Cl. In the tin series, however transmetallation is the main process when MeCu, H2CCHCu or PhCu are used. The allenyl compounds in which R is (trimethylsilyl)ethynyl or 4,4-dimethyl-1,2-pentadienyl can