Phase-transfer-catalysed asymmetric synthesis of tetrasubstituted allenes
作者:Takuya Hashimoto、Kazuki Sakata、Fumiko Tamakuni、Mark J. Dutton、Keiji Maruoka
DOI:10.1038/nchem.1567
日期:2013.3
Allenes are molecules based on three carbons connected by two cumulated carbon–carbon double bonds. Given their axially chiral nature and unique reactivity, substituted allenes have a variety of applications in organic chemistry as key synthetic intermediates and directly as part of biologically active compounds. Although the demands for these motivated many endeavours to make axially chiral, substituted
Diethyl Phosphite Initiated Coupling of α-Ketoesters with Imines for Synthesis of α-Phosphonyloxy-β-amino Acid Derivatives and Aziridine-2-carboxylates
作者:Jin Jiang、Hui Liu、Chong-Dao Lu、Yan-Jun Xu
DOI:10.1021/acs.orglett.6b00273
日期:2016.2.19
Coupling of α-ketoesters with imines initiated by diethylphosphite in the presence of alkaline metal hexamethyldisilazides is reported. Base-promoted addition of diethylphosphite to α-ketoesters, followed by [1,2]-phosphonate/phosphate rearrangement, generates α-phosphonyloxy enolates that are subsequently intercepted by imines. The use of suitable azomethine coupling partners allows selective construction
Invertible Enantioselectivity in 6′-Deoxy-6′-acylamino-β-isocupreidine-Catalyzed Asymmetric Aza-Morita−Baylis−Hillman Reaction: Key Role of Achiral Additive
作者:Nacim Abermil、Géraldine Masson、Jieping Zhu
DOI:10.1021/ol901920s
日期:2009.10.15
(1e)-catalyzed aza-Morita−Baylis−Hillmanreaction between N-sulfonylimines 3 and alkyl vinyl ketones 4 produced the (R)-enriched adducts 5. By adding a catalytic amount of β-naphthol (2a), the enantioselectivity of the same reaction was inversed leading to (S)-5 in excellent yields and enantioselectivities. Both aromatic and aliphaticimines are accepted as substrates for this reaction.
Mix and go: The quinidine amide 1 catalyzed [2+2] cycloaddition between N‐sulfonylimines 2 and alkyl 2,3‐butadienoates 3 afforded the R‐configured azetidines 4 in excellent yields and enantioselectivities (M.S.=molecular sieve). The S enantiomer was obtained when a quinine amide catalyst, the pseudoenantiomer of 1, was used.
P(NMe<sub>2</sub>)<sub>3</sub>-Mediated Aziridination of Imines with α-Ketoesters for Synthesis of Aziridine-2-carboxylates
作者:Jin Jiang、Hui Liu、Chong-Dao Lu、Yan-Jun Xu
DOI:10.1021/acs.joc.6b02669
日期:2017.1.6
Aziridination of N-sulfonyl imines with α-ketoesters in the presence of P(NMe2)3 is reported. Adducts derived from trivalentphosphorusreagents and α-ketoesters are effectively intercepted by imines, affording a range of aziridine-2-carboxylates. The diastereoselectivity of the reaction depends on steric hindrance from substituents on the substrates.