Enantioselective syntheses of d-erythro-sphingosine and phytosphingosine from simple achiral aldehydes using catalytic asymmetric aldol reactions as key steps
作者:Shū Kobayashi、Takaomi Hayashi、Takashi Kawasuji
DOI:10.1016/0040-4039(94)88514-1
日期:1994.12
d-erythro-sphingosine and phytosphingosine were prepared from simple achiral aldehydes, trimethylsilylpropynal and acrolein, by using chiral tin(II) Lewis acid-catalyzed asymmetric aldol reactions as key steps.
D-gluco-configured buildingblock derived from D-(+)-gluconolactone has served as a common chiral template for the synthesis of enantiopure D- and L-xylo-configured 1,2,3,4-alkane tetrols. This has enabled synthesis of medicinally important guggultetrols and their enantiomers from a common starting point. Wittig and Grignard reactions are the key steps used for the incorporation of lipophilic chain
作者:Richard A. Bartsch、Leah P. Bitalac、Charles L. Cowey、Sadik Elshani、Mi-Ja Goo、Vincent J. Huber、Sheryl N. Ivy、Youngchan Jang、Russell J. Johnson、Jong Seung Kim、Elzbieta Luboch、Joseph A. Mcdonough、Michael J. Pugia、Byungki Son、Qiang Zhao
DOI:10.1002/jhet.5570370554
日期:2000.9
Synthetic routes to forty-four dibenzocrown ether alcohols are reported. The new crown ether com pounds are based on a sym-dibenzo-16-crown-5 platform. Most have a hydroxy group and an alkyl, aryl, aralkyl, alkenyl, alkynyl, or perfluoroalkyl group on the central carbon of the three-carbon bridge. Others have substituted benzene rings and either a hydroxy or -O(CH2)nOH group attached to the central
Synthesis and mesomorphic properties of 1,1-difluoroalkyl-substituted biphenylthienyl and terphenyl liquid crystals. A comparative study of mesomorphic behavior relative to alkyl, alkoxy and alkanoyl analogsElectronic supplementary information (ESI) available: experimental details for compounds 4, 9, 10, 12, 15–19, 25–39, 45 and 49. See http://www.rsc.org/suppdata/jm/b1/b102059p/
作者:Andre A. Kiryanov、Paul Sampson、Alexander J. Seed
DOI:10.1039/b102059p
日期:2001.11.23
A variety of biphenylthienyl and terphenyl-based liquid crystalline materials were prepared that incorporate a 1,1-difluoropentyl terminal group. The mesogenic properties of these compounds were compared and contrasted with analogs where the CF2 moiety was replaced by a -CH2-, -O- or -CO- group. The 1,1-difluoroalkyl group is unique in its behavior and tends to promote orthogonal smectic phase behavior.