catalytic enantio- and diastereoselective nitro-Mannichreaction of α-amido sulfones in the mixed solvent of toluene/H2O has been realized using a phase-transfer catalyst (PTC) derived from cinchona alkaloids and N-benzotriazole. It performed well over a wide range of substrates to give the desired products in good yields (up to 94%) with excellent enantioselectivities (up to 99% ee) and diastereoselectivities
使用衍生自金鸡纳生物碱和N-苯并三唑的相转移催化剂(PTC)实现了α-酰胺基砜在甲苯/ H 2 O混合溶剂中的催化对映体和非对映体的硝基曼尼希反应。它在各种底物上均表现良好,以高收率(最高94%)提供所需的产品,并具有出色的对映选择性(最高99%ee)和非对映选择性(最高99:1)。
Asymmetric Organocatalytic Formal Aza-Michael Addition of Ammonia to Nitroalkenes
The formal addition of ammonia to nitroalkenes, affording optically active β‐amino nitro compounds in high yields and enantioselectivities, is presented (see scheme). The approach is based on a novel thiourea‐catalyzed aza‐Michael reaction, by which benzophenone imine serves as a masked ammonia equivalent, which is released by hydrolysis.
Bifunctional asymmetric phase-transfercatalysts bearing multiple hydrogen-bonding donors have rarely been explored. The first quaternary ammonium type of these catalysts derived from cinchona alkaloids were readily prepared and found to be highly efficient catalysts for asymmetric nitro-Mannichreactions of amidosulfones. Compared with previous reports, very broad substrate generality was observed
A New Family of Cinchona-Derived Bifunctional Asymmetric Phase-Transfer Catalysts: Application to the Enantio- and Diastereoselective Nitro-Mannich Reaction of Amidosulfones
作者:Kayli M. Johnson、Matt S. Rattley、Filippo Sladojevich、David M. Barber、Marta G. Nuñez、Anna M. Goldys、Darren J. Dixon
DOI:10.1021/ol300779x
日期:2012.5.18
family of bifunctional H-bond donor phase-transfer catalysts derived from cinchona alkaloids has been developed and evaluated in the enantio- and diastereoselective nitro-Mannich reaction of in situgenerated N-Boc-protected imines of aliphatic, aromatic, and heteroaromatic aldehydes. Under optimal conditions, good reactivity and high diastereoselectivities (up to 24:1 dr) and enantioselectivities (up to
combination of a new bifunctional phosphine and an acrylate generate a zwitterion in situ and it serves as an efficient catalyst for asymmetric reactions through a homogeneous ion‐pairing mode. This new catalytic system has been successfully applied to Mannich‐typereactions to give excellent results and it demonstrates a broad substrate scope. Such reactivity is not accessible with general organophosphine catalytic