1108740-06-2Relevant 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.
Addressing the configuration stability of lithiated secondary benzylic carbamates for the development of a noncryogenic stereospecific boronate rearrangement
Fandrick, Keith R.,Patel, Nitinchandra D.,Mulder, Jason A.,Gao, Joe,Konrad, Michael,Archer, Elizabeth,Buono, Frederic G.,Duran, Adil,Schmid, Rolf,Daeubler, Juergen,Fandrick, Daniel R.,Ma, Shengli,Grinberg, Nelu,Lee, Heewon,Busacca, Carl A.,Song, Jinhua J.,Yee, Nathan K.,Senanayake, Chris H.
, p. 4360 - 4363 (2015/02/19)
A practical noncryogenic process for the Aggarwal stereospecific boronate rearrangement with chiral secondary benzylic carbamates has been developed. The use of LDA instead of sec-BuLi combined with an in situ trapping of the unstable lithiated carbamate was critical to success. Furthermore, this new process increased the substrate scope to include the versatile aryl iodide and bromide substrates. The methodology was applied to a diverse array of substrates and was demonstrated on multikilogram scale.
