Chiral iminophosphorane catalyzed asymmetric Henry reaction of α,β-alkynyl ketoesters
作者:Yanxia Zhang、Xin-Yan Wu、Jianwei Han
DOI:10.1016/j.cclet.2019.04.042
日期:2019.8
Abstract α,β-Alkynyl ketoesters were introduced to the enantioselective Henry reaction (nitroaldol condensation) with nitromethane catalyzed by tartaric acid derived chiral iminophosphoranes. As such, a variety of optically active β-nitro-substituted tertiary alcohols bearing alkyne moieties were obtained in good to excellent yields (42%–99%) and moderate to good level of enantiomeric excess (up to
An Achiral-Acid-Induced Switch in the Enantioselectivity of a Chiral cis-Diamine-Based Organocatalyst for Asymmetric Aldol and Mannich Reactions
作者:Shin A. Moteki、Jianwei Han、Satoru Arimitsu、Matsujiro Akakura、Keiji Nakayama、Keiji Maruoka
DOI:10.1002/anie.201107239
日期:2012.1.27
Pick and choose: The asymmetric synthesis of two different enantiomeric products has been achieved through the use of a single organocatalyst with or without achiral organic acid additives (see scheme). These additives may assist in altering the substrate orientations at the catalytic center, leading to efficient enantiomeric inversions in both aldol and Mannich products.
A highly practical and stereoselective route to 1,4-dicarbonyl 2,3-dihaloalkenes is presented. The strategy involves bench-stable unprotected alkynyl hydrazones and commercially available N-halosuccinimides that provide γ-oxo-α,β-(Z)-dihaloenoates in excellent yields with complete Z-selectivity. The protocol also furnishes vicinal dihaloalkenes with two different halogen atoms. Also, a straightforward
提出了一种高度实用且立体选择性的 1,4-二羰基 2,3-二卤代烯烃合成路线。该策略涉及实验室稳定的未保护的炔基腙和市售的N -卤代琥珀酰亚胺,它们以优异的收率提供具有完全Z选择性的 γ-氧代-α,β-( Z )-二卤代烯酸酯。该方案还提供了具有两个不同卤素原子的邻位二卤代烯烃。此外,还证明了从容易获得的 2-氧代-3-丁酸中直接一锅法合成二卤代烯酸。此外,还探索了 4-oxo-2,3-dibromoenoates 的潜在合成转化,其中包括有价值的五元和六元杂环的合成。
Doyle–Kirmse Reaction on Alkynyl Hydrazone Carboxylates: Synthesis of 1,4-Allenyne and 1,5-Enyne Thioaryl Carboxylates
The first Doyle–Kirmse reaction on alkynyl diazoacetates using allyl/propargyl sulfides is reported. The development provides diversified 1,5-enyne and 1,4-allenyne thioaryl carboxylates in good yields under ligand-/additive-free AuCl and Rh2(OAc)4 catalysis, respectively (48 examples, up to 96% yield). The study demonstrated the dual role of allyl sulfide as a ligand and substrate. Also, we have exemplified
Rhodium(II)-Catalyzed Alkynyl Carbene Insertion into N–H Bonds
作者:Akashdeep Sharma、Himani Vaid、Riya Kotwal、Zuhaib N. Mughal、Ramani Gurubrahamam
DOI:10.1021/acs.orglett.4c01345
日期:2024.6.14
The first insertion of an alkynyl carbene into N–H bonds under Rh-catalysis is developed. Alkynyl hydrazone carboxylates are used as donor–acceptor carbene precursors and are exquisitely inserted into the N–H bonds of various amines, amides, and 1,2-diamines. A wide variety of 3-alkynyl 3,4-dihydroquinoxalin-2(1H)-ones and densely functionalized α-alkynyl α-amino esters are obtained in good to excellent