Stereoselective Synthesis of Polysubstituted Alkenes through a Phosphine-Mediated Three-Component System of Aldehydes, α-Halo Carbonyl Compounds, and Terminal Alkenes
作者:Da-Neng Liu、Shi-Kai Tian
DOI:10.1002/chem.200900177
日期:2009.4.27
mediate the one‐pot Wittig reaction of aldehydes with α‐halo carbonylcompounds for the synthesis of 1,2‐disubstituted and trisubstituted alkenes in an excellent stereoselective fashion. Furthermore, the first one‐pot, three‐component reaction of aldehydes, α‐halo acetates, and terminalalkenes has been developed in the presence of PPh3 to produce trisubstituted alkenes with excellent E selectivity (see
bromolactones (5) stereoselectively produced by the asymmetric bromolactonisation of (S)-N-(α,β-unsaturated) acylprolines(3), were elaborated to highly opticallyactive 2(R),3(S)-epoxyaldehydes(8)(84–98% ee) by successive epoxide formation and reductive cleavage of the proline moiety. The overall process constitutes a highly efficient asymmetric synthesis of 8 from α,β-unsaturated acids(1).
The reaction of a series of 2,3-epoxy alcohols and the corresponding formates, acetates, and benzoates promoted by Cp 2 TiCl has been studied. The different outcome of the reaction of epoxy derivatives has been rationalized in terms of mechanistically biased processes. After homolytic oxirane cleavage, four main types of reaction were found: dehydroxylation, decarboxylation, dehydrogenation, and deoxygenation
Ink jet inks and liquid developers are disclosed which contain coloured particles comprising hydrophilic silica particles, to the surfaces of which dyes are covalently bonded through silane coupling agents. The ink jet inks generally comprise a liquid medium and a plurality of the coloured silica particles. The liquid developers generally comprise a liquid medium, a resin, a pluraltiy of the coloured silica particles, and a charge-control agent. The particles are prepared by a process which comprises reacting hydrophilic silica particles with a silane coupling agent in the absence of water to form particles having covalently attached thereto coupling agents, followed by reacting a dye with the coupling agent attached to the silica particles.