A series of unsymmetricallysubstituted diastereoisomeric (Ra,R) and (Sa,R) bipyridine N,N′‐dioxides were tested as catalysts for the enantioselective allylation of various aldehydes. Homoallylic alcohols were obtained with enantiopurities of up to 99 % ee.
Synthetically amenable amide derivatives of tosylated-amino acids as organocatalysts for enantioselective allylation of aldehydes: computational rationale for enantioselectivity
作者:Debashis Ghosh、Debashis Sahu、S. Saravanan、Sayed H. R. Abdi、Bishwajit Ganguly、Noor-ul H. Khan、Rukhsana I. Kureshy、Hari C. Bajaj
DOI:10.1039/c3ob27513b
日期:——
A phenylalanine derived chiral amide is developed that serves as an effective organocatalyst for the reaction of allyltrichlorosilane with aryl, hetero-aryl and α,β-unsaturated aldehydes to afford the desired homoallylic alcohols in good yield (up to 90%) and high enantioselectivity (up to 99%). The experimental results and DFT calculations suggest that para substituted aromatic aldehydes as substrate show higher ee in the product than their ortho/meta counterparts. The 1H and 13C NMR spectra study corroborated the calculated results. The chiral organocatalyst can be easily synthesized from optically pure phenylalanine in two simple steps with 90% overall yield.
as Lewis base catalysts are reported. Lewis bases containing the 3,5-bis(trifluoromethyl)phenyl group were found to be significantly more enantioselective for a wider range of substrates than those bearing aromatic residues that are not strongly electron-deficient in the allylation of aldehydes with allyltrichlorosilane. Also, optically pure 3,3′-dibromo-1,1′-biisoquinoline N,N′-dioxide that has not
TetraPh-Tol-BITIOPO: a new atropisomeric 3,3′-bithiophene based phosphine oxide as an organocatalyst in Lewis base-catalyzed Lewis acid mediated reactions
作者:Abbinante Vincenzo Mirco、Benaglia Maurizio、Rossi Sergio、Benincori Tiziana、Cirilli Roberto、Pierini Marco
DOI:10.1039/c9ob01297d
日期:——
catalyst was able to promote the allylation of aldehydes with allyltrichlorosilane in up to 98% yield and up to 96% enantiomeric excess (ee), and the direct aldol reaction to afford β-hydroxy ketones and β-hydroxy thioesters, with good chemical yields and modest stereochemical efficiency. Computational studies helped to elucidate and to rationalize the stereochemical outcome of the reactions catalyzed
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