Ligand-Promoted Asymmetric Imino-Reformatsky Reaction of Ethyl Dibromofluoroacetate
摘要:
An enantioselective Reformatsky reaction has been developed for the reaction of ethyl dibromofluoroacetate (1) with an imine. This method represents the first ligand-promoted imino-Reformatslcy approach to use a halofluoroacetate. The use of an amino alcohol ligand allowed for the preparation of enantioenriched alpha-bromo-alpha-fluoro-beta-lactams in good yields with enantioselectivities up to 96% ee. This process also provided access to beta-lactam rings bearing two stereogenic centers.
A new library of modular amino phosphite ligands obtained in a few synthetic steps from enantiopure amino alcohols has been tested in asymmetric Pd‐catalyzed allylicsubstitution. The modular ligand design is crucial to find highly selective catalysts for each substrate type using a wide range of C‐, N‐, and O‐nucleophiles. A DFT study of the species responsible for the enantiocontrol was used to optimize
Carbonylamino Pyrrolopyrazole compounds of formula I, compositions including these compounds and methods of their use are provided. Preferred compounds of formula I have activity as protein kinase inhibitors, including as inhibitors of PAK4.
作者:Iain Coldham、Sophie Raimbault、Praful T. Chovatia、Jignesh J. Patel、Daniele Leonori、Nadeem S. Sheikh、David T. E. Whittaker
DOI:10.1039/b810988e
日期:——
Dynamic thermodynamic resolution of N-Boc-2-lithiopiperidine is possible using a chiral ligand; the two enantiomers of this organolithium can be resolved with selectivities of up to 85 : 15 from a selection of 26 chiral diamino-alkoxide ligands screened.
Enantiomerically pure β-hydroxyalkyl and β-aminoalkyl ferrocenyl sulfides have been synthesized in good yields from mercaptoferrocene and amino alcohol derivatives. Primary β-aminoalkyl sulfides allowed the synthesis of tetrahydro-1,4-thiazepines containing the ferrocene moiety with good diastereoselectivity and β-iminoalkyl sulfides. Some of these derivatives have successfully been employed as ligands
Optimisation of enantioselectivity for the chiral base-mediated rearrangement of bis-protected meso-4,5-dihydroxycyclohexene oxides: asymmetric synthesis of 4-deoxyconduritols and conduritol F
作者:Simon E de Sousa、Peter O'Brien、Christopher D Pilgram
DOI:10.1016/s0040-4020(02)00370-8
日期:2002.6
based on diastereoselective epoxidation of a cyclohexene followed by chiral lithium amide-mediated epoxide rearrangement has been used to synthesise an allylic alcoholbuildingblock of >95% ee. The key step is the enantioselective rearrangement of a bis-protected meso-4,5-dihydroxycyclohexene oxide. A range of protecting groups and chiral base structures were surveyed in order to find the optimum protocol