122nd General Meeting of the KCS

Type Oral Presentation
Area Oral Presentations for Young Scholars in Organic Division
Room No. Room 325A+B
Time THU 09:15-:
Code ORGN.O-2
Subject Chemo- and Stereoselective Allylboration of Aldehydes and Cyclic Aldimines with Allylic-gem-diboronate Ester
Authors Jinyoung Park, Yeosan Lee, Seung Hwan Cho*
Department of Chemistry, Pohang University of Science and Technology, Korea
Abstract The preparation of new types of organoboron compounds is especially important owing to their stability and ability to undergo a wide range of organic transformations In recent years, gem-diborylalkanes have emerged as attractive synthetic intermediates for synthesizing organoborons via transitionmetal-catalyzed or transition-metal-free chemo- and stereoselective transformations with suitable electrophiles. Although considerable advances have been made in recent years, most of the methods developed employed alkyl-substituted gem-diboron reagents, the use of which necessitates strong base (MOH or MO-t-Bu, M= Li, Na, K) to activate one of the pinacolato boron(Bpin) units of the gem-diborylalkane chemoselectively through the formation of an α-boryl alkyl metal species or α-borylcarbanion. In this presentation, we report a highly chemo- and stereo selective crotylation of aldehydes and cyclic aldimines with allylic-gem diboronate ester as a new type of organoboron reagent. The allylic-gem-diboronate ester undergoes the crotylation with aldehydes and cyclic aldimines in excellent stereoselectivity, forming anti-5,6-disubstituted oxaborinin-2-ols or (E)-δ-boryl-anti-homoallylic amines in high efficiency. The reaction shows a wide range of substrate scope and excellent functional group tolerance. The synthetic applications of the obtained products, including stereospecific C−C, C−O, and C−Cl bond formation, are also demonstrated.
E-mail jinyoung@postech.ac.kr