Concise Syntheses of (−)- and (+)-Syringolide 1 and (−)-Δ<sup>7</sup>-Syringolide 1
作者:Chun-min Zeng、Sharon L. Midland、Noel T. Keen、James J. Sims
DOI:10.1021/jo970461b
日期:1997.7.1
(-)- and (+)-Syringolide 1 have been synthesized from 2,3-O-isopropylidene-beta-threo-pentulofuranose (1), which was readily prepared from D- or L-xylose, respectively. Condensation of 1 with 3-oxooctanoic acid and treatment of the ester with TFA:H2O (9:1) produced syringolide 1 in 6.3% yield for the two steps. According to the same synthetic route by replacing 3-oxooctanoic acid with 3-oxo-7-octenoic acid, (-)-Delta(7)-syringolide 1 was prepared in 5.8% yield. Primary P-keto esters of arabinulose and fructose were also prepared to test the selectivity of the biomimetic cyclization to form syringolide analogs.
Isomerisation of aldoses in pyridine in the presence of aluminium oxide
作者:Dag Ekeberg、Svein Morgenlie、Yngve Stenstrøm
DOI:10.1016/j.carres.2004.12.006
日期:2005.2
Addition of aluminium oxide to boiling pyridine solutions Of D-xylose, L-arabinose, D-mannose and D-glucose strongly increased the reaction rate of the aldose-ketose transformation. The maximum content of 2-ketose was reached after less than 2 h for the aldopentoses and 3 h for the aldohexoses. D-threo-2-Pentulose (xylulose) was prepared from D-xylose, and isolated as its O-isopropylidene derivative, the yield was nearly twice that compared to that usually obtained in the classical Lobry de Bruyn-Alberda van Ekenstein transformation in pyridine. (C) 2004 Elsevier Ltd. All rights reserved.