4586-94-1Relevant academic research and scientific papers
Stereoselective [4+2]-Cycloaddition with Chiral Alkenylboranes
Brown, M. Kevin,Houk, K. N.,Ni, Dongshun,Witherspoon, Brittany P.,Zhang, Hong,Zhou, Chen
supporting information, p. 11432 - 11439 (2020/05/18)
A method for the stereoselective [4+2]-cycloaddition of alkenylboranes and dienes is presented. This transformation was accomplished through the introduction of a new strategy that involves the use of chiral N-protonated alkenyl oxazaborolidines as dieneophiles. The reaction leads to the formation of products that can be readily derivatized to more complex structural motifs through stereospecific transformations of the C?B bond such as oxidation and homologation. Detailed computation evaluation of the reaction has uncovered a surprising role of the counterion on stereoselectivity.
Tuning of vinylborane dienophilicity. Optimization of reactivity, regioselectivity, endo stereoselectivity, and reagent stability
Singleton, Daniel A.,Martinez, Jose P.,Watson, Jose V.,Ndip, Grace M.
, p. 5831 - 5838 (2007/10/02)
Simple syntheses of some vinylboranes are reported, and their properties in Diels-Alder reactions are compared. Vinyl-3,6-dimethylborepane was the most stable simple vinylborane examined, and appears to be indefinitely stable at 25°C. Surprisingly, trivinylborane is the most reactive, and reacts about 18 times faster than the vinyldialkylboranes with cyclopentadiene. Vinyl-9-BBN is the most regioselective dienophile, in keeping with principally steric control of regioselectivity in Diels-Alder reactions of vinylboranes. All the dienophiles display high endo-stereoselectivity with piperylene, but vinyl-3,6-dimethylborepane displays significantly improved stereoselectivity with cyclopentadiene. In general, by choice of alkyl-substituents on boron, the reactivity, regioselectivity, endo-stereo selectivity, and stability of vinylboranes can be optimized.
