Asymmetric Michael Addition of Ketones to Alkylidene Malonates and Allylidene Malonates via Enamine–Metal Lewis Acid Bifunctional Catalysis
作者:Lu Liu、Ryan Sarkisian、Zhenghu Xu、Hong Wang
DOI:10.1021/jo301070s
日期:2012.9.7
Novel enamine–metal Lewis acid bifunctional catalysts were successfully applied to the asymmetric Michaeladdition of ketones to alkylidenemalonates, offering excellent stereoselectivity (up to >99% ee and >99:1 dr). The asymmetric Michaeladdition of ketones to allylidene malonates was also achieved.
Accessing Dihydro-1,2-oxazine via Cloke–Wilson-Type Annulation of Cyclopropyl Carbonyls: Application toward the Diastereoselective Synthesis of Pyrrolo[1,2-<i>b</i>][1,2]oxazine
作者:Pankaj Kumar、Rakesh Kumar、Prabal Banerjee
DOI:10.1021/acs.joc.0c00531
日期:2020.5.15
A convenient additive-free synthesis of dihydro-4H-1,2-oxazines via a Cloke-Wilson-type ring expansion of the aryl-substituted cyclopropane carbaldehydes with the hydroxylamine salt is introduced. Comparatively less active cyclopropyl ketones also follow a similar protocol if supplemented by catalytic p-toluene sulfonic acid monohydrate. The transformation is performed in an open-to-air flask as it
Regioselective 1,4- and 1,6-Conjugate Additions of Grignard Reagent-Derived Organozinc(II)ates to Polyconjugated Esters
作者:Manabu Hatano、Mai Mizuno、Kazuaki Ishihara
DOI:10.1021/acs.orglett.6b01774
日期:2016.9.16
Regioselective synthetic methods were developed for 1,4- and 1,6-conjugateadditions of Grignard reagent-derived organozinc(II)ates to malonate-derived polyconjugated esters. By taking advantage of the tight ion-pair control of organozinc(II)ates, it was possible to switch between 1,4- and 1,6-conjugateadditions by introducing a terminal ethoxy moiety in the conjugation.
Lewis Acid-Catalyzed [3+2] Cycloaddition of Donor-Acceptor Cyclopropanes and Enamines: Enantioselective Synthesis of Nitrogen-Functionalized Cyclopentane Derivatives
作者:Kamal Verma、Prabal Banerjee
DOI:10.1002/adsc.201600221
日期:2016.6.30
efficient method for the synthesis of nitrogen‐functionalized cyclopentane derivatives via [3+2] cycloaddition of enamines with donor‐acceptor cyclopropanes in the presence of catalytic amounts of various Lewisacids at room temperature has been developed; furthermore, the corresponding β‐amino acid was synthesized by monodecarboxylation and hydrogenolysis. An enantioenriched synthesis of nitrogen‐functionalized
Palladium-catalyzed asymmetric 1,6-addition of diarylphosphines to α,β,γ,δ-unsaturated sulfonic esters: controlling regioselectivity by rational selection of electron-withdrawing groups
作者:Junzhu Lu、Jinxing Ye、Wei-Liang Duan
DOI:10.1039/c3cc46290k
日期:——
Palladium-catalyzed asymmetric 1,6-addition of diarylphosphines to electron-deficient dienes was developed through rational selection of electron-withdrawing groups on the dienes. Various chiral allylic phosphine derivatives were synthesized in good yields with high enantioselectivity (up to 96% ee).