Bi(cyclopentyl)diol-Derived Boronates in Highly Enantioselective Chiral Phosphoric Acid-Catalyzed Allylation, Propargylation, and Crotylation of Aldehydes
作者:Jinping Yuan、Pankaj Jain、Jon C. Antilla
DOI:10.1021/acs.joc.0c01646
日期:2020.10.16
catalytic addition of bi(cyclopentyl)diol-derived boronates to aldehydes promoted by chiralphosphoricacids, allowing for the formation of enantioenriched homoallylic, propargylic, and crotylic alcohols (up to >99% enantiomeric excess (ee), diastereomeric ratio (dr) >20:1). These boronate substrates provided superior enantioselectivities, allowing for the reactions to proceed with low catalyst loading
Allylation Reactions of Aldehydes with Allylboronates in Aqueous Media: Unique Reactivity and Selectivity that are Only Observed in the Presence of Water
Zn(OH)2‐catalyzed allylation reactions of aldehydes with allylboronates in aqueous media have been developed. In contrast to conventional allylboration reactions of aldehydes in organic solvents, the α‐addition products were obtained exclusively. A catalytic cycle in which the allylzinc species was generated through a B‐to‐Zn exchange process is proposed and kinetic studies were performed. The key
Wittig rearrangement of allyl 2-thiophenemethyl ethers was studied. Deprotonation of allyl 2-thiophenemethyl ethers (1a-d) occurred preferentially either the alpha- or the alpha'-position, depending on three kinds of BuLi. Thiophenemethanol and -ethanol derivatives were obtained as products of [2,31 and [1,2] sigmatropic rearrangements, respectively.
WUTS P. G. M.; CALLEN G. R., SYNTH. COMMUN., 16,(1986) N 14, 1833-1837