EFFICIENT CONVERSION OF CARBOXYLIC ACIDS INTO THIOL ESTERS
作者:Takehisa Kunieda、Yoshihiro Abe、Masaaki Hirobe
DOI:10.1246/cl.1981.1427
日期:1981.10.5
A facile and direct preparation of thiol esters from carboxylic acids and thiols using diphenyl 2-oxo-3-oxazolinylphosphonate in the presence of triethylamine is described.
New phosphorylating agents for general synthesis of mixed phosphate esters
作者:Tomohisa Nagamatsu、Takehisa Kunieda
DOI:10.1016/s0040-4039(00)96128-8
日期:——
effective procedure has been developed for the general synthesis of mixed alkyl or arylphosphate esters by metal-catalyzed phosphorylation of alcohols with aryl bis(2-oxo-3-oxazolinyl)phosphinate. Among metallic acetylacetonates examined as catalysts, the zirconium complex was the most effective as in activity order of Zr(IV)> Ce(III)> Zn(II)> Mn(III)> Mn(II)-complexes.
promising method for the versatile synthesis of chiral 2-amino alcohols is provided by the enantioselective functionalization of the olefinic moiety of the simple heterocycle, 2-oxazolone, involving a stereodefined introduction of easily replaceable groups followed by stepwise substitution. Versatility of this method is shown in chiral synthesis of unusual hydroxy amino acids such as statine and hydroxyglutamic
The intramolecular ruthenium(II)-catalyzed radical addition of the trichloroacetyl pendant group to the 2-oxazolone skeleton is greatly enhanced in the presence of catalytic Lewis acids including rare earth metal triflates, thus providing a convenient route to a highly potential chiral synthon for vic-amino alcohols.
The thermal reaction of 3-[(IS)-2-alkoxy-1-apocamphanecarbonyl]-2-oxazolones (21a-c) with dialkyl azodicarboxylates (9) results in exclusive formation of [4 + 2] type cycloadducts (22 and 23) with moderate levels of diastereofacial selection (up to 72% d.e.). The diastereomers thus obtained were readily purified and subsequent treatment with acidic methanol followed by removal of the auxiliary with LiBH4/MeOH (1:2) gave optically pure 4-methoxy-5-hydrazino-2-oxazolidinones (26 and 27), which serve as alpha-aminoaldehyde templates useful for the synthesis of a wide variety of optically active alpha-amino acids as well as 4-alkyl and 4-aryl-2-oxazolidinones. (C) 1997, Elsevier Science Ltd.