7216-97-9Relevant academic research and scientific papers
Construction of multiple, contiguous quaternary stereocenters in acyclic molecules by lithiation-borylation
Watson, Charlotte G.,Balanta, Angelica,Elford, Tim G.,Essafi, Stphanie,Harvey, Jeremy N.,Aggarwal, Varinder K.
supporting information, p. 17370 - 17373 (2015/02/05)
Lithiation of carbamates followed by borylation provides a powerful method for the homologation of boron reagents. However, when applied to hindered systems (secondary carbamates with tBu-boronic esters) for the construction of two quaternary centers, thi
One-pot multicomponent coupling methods for the synthesis of diastereo- and enantioenriched (Z)-trisubstituted allylic alcohols
Kerrigan, Michael H.,Jeon, Sang-Jin,Chen, Young K.,Salvi, Luca,Carroll, Patrick J.,Walsh, Patrick J.
, p. 8434 - 8445 (2009/10/23)
(Z)-Trisubstituted allylic alcohols are widespread structural motifs in natural products and biologically active compounds but are difficult to directly prepare. Introduced herein is a general one-pot multicomponent coupling method for the synthesis of (Z)-α,α,β-trisubstituted allylic alcohols. (Z)-Trisubstituted vinylzinc reagents are formed in situ by initial hydroboration of 1-bromo-1-alkynes. Addition of dialkylzinc reagents induces a 1,2-metalate rearrangement that is followed by a boron-to-zinc transmetalation. The resulting vinylzinc reagents addto a variety of prochiral aldehydes to produce racemic (Z)-trisubstitut ed allylic alcohols. When enantioenriched aldehyde substrates are employed, (Z)-trisubstituted allylic alcohols are isolated with high dr (>20:1in many cases). For example, vinylation of enantioenriched benzyl-prote cted α- and β-hydroxy propanal derivatives furnished the expected anti-Felkin addition products via chelation control. Surprisingly, silyl-protected α-hydroxy aldehydes also afford anti-Felkin addition products. A protocol for the catalytic asymmetric addition of (Z)-trisubstituted vinylzinc reagents to prochiral aldehydes with a (-)-MIB-based catalyst has also been developed. Several additives were investigatedas inhibitors of the Lewis acidic alkylzinc halide byproducts, which pr omote the background reaction to form the racemate. R-Ethyl and R-cyclohexyl (Z)-trisubstituted allylic alcohols can now be synthesized with excellent levels of enantioselectivity in the presence of diamine inhibitors.
