133038-74-1Relevant articles and documents
Stereospecific Synthesis of Alkenes by Eliminative Cross-Coupling of Enantioenriched sp3-Hybridized Carbenoids
Wu, Zhenhua,Sun, Xun,Potter, Kristin,Cao, Yang,Zakharov, Lev N.,Blakemore, Paul R.
, p. 12285 - 12289 (2016/10/13)
1-Aryl-1,2-dialkylethenes were generated by a sequence of electrophilic substitution, 1,2-metalate rearrangement, and β-elimination initiated by the addition of enantioenriched α-(carbamoyloxy)alkylboronates to enantioenriched lithiated carbamates. The carbenoid stereochemical pairing [i.e., “like”=(S)+(S) or “unlike”=(S)+(R)] and the elimination mechanism (syn or anti), not substituent effects, determined the configuration of the trisubstituted alkene target. For example, (Z)-2,5-diphenyl-2-pentene was produced in 70 % yield with E/Z=5:95 by a like combination of Li and B carbenoids and syn (thermal) elimination whereas the E isomer was obtained in the same yield with E/Z>98:2 by an otherwise identical process involving an unlike stereochemical pairing. The concept elaborated overcomes an intrinsic limitation of traditional strategies for direct connective alkene synthesis, which cannot realize meaningful stereochemical bias unless the alkene substituents are strongly differentiated.
Asymmetric synthesis of 1-heteroaryl-1-arylalkyl tertiary alcohols and 1-pyridyl-1-arylethanes by lithiation-borylation methodology
Watson, Charlotte G.,Aggarwal, Varinder K.
, p. 1346 - 1349 (2013/05/09)
The synthesis of highly enantioenriched α-heterocyclic tertiary alcohols has been achieved via lithiation-borylation of a configurationally stable lithiated carbamate and heterocyclic pinacol boronic esters followed by oxidation. Protodeboronation of the α-heterocyclic tertiary boronic esters using TBAF·3H2O or CsF gave highly enantioenriched 1-pyridyl-1-arylethanes in high er.
Generation of a configurationally stable, enantioenriched α-oxy-α-methylbenzyllithium: Stereodivergence of its electrophilic substitution
Carstens, Axel,Hoppe, Dieter
, p. 6097 - 6108 (2007/10/02)
The deprotonation of (R)- or (S)-1-phenylethyl N,N-diisopropylcarbamate with s-butyllithium/TMEDA in unpolar solvents (e.g. ether or hexane) at -78°C produces configurationally stable ion pairs which are substituted stereospecifically by different electro