The metathesis reaction for side chain construction in carbocyclic sinefungin analogue synthesis
作者:Qi Chen、Chong Liu、Tetyana S. Shulyak、Stewart W. Schneller
DOI:10.1016/j.tet.2013.12.030
日期:2014.1
The naturally occurring nucleoside sinefungin has found considerable use in biological investigations. More extensive sinefungin studies have been limited because few analogues have been reported due to the synthetic challenges associated with such studies. Reported herein are preparative ways to two carbocyclic sinefungin analogues: 6'-deaminocarbocyclic sinefungin and (S)-6'-hydroxy-6'-deamino-carbocyclic sinefimgin. The synthetic routes were made efficient and practical by the application of two metathesis reactions employing second generation Grubbs catalyst. (C) 2013 Elsevier Ltd. All rights reserved.
Enantiospecific Synthesis of (−)-Slaframine and Related Hydroxylated Indolizidines. Utilization of a Nucleophilic Alaninol Synthon Derived from Serine<sup>1</sup>
作者:Mukund P. Sibi、James W. Christensen
DOI:10.1021/jo9908546
日期:1999.8.1
A general methodology for the synthesis of indolizidine alkaloids delta-coniceine (12), 1-hydroxyindolizidine (20), desacetoxy slaframine (24), slaframine (34), and an analogue (37) has been developed. This convergent approach utilizes the available chirality in proline and serine and is conceptually different from other approaches. A highly stereoselective coupling of the prolinals with a nucleophilic alaninol synthon provides the precursors for the key cyclization. A novel thermolytic annulation of an oxazolidinone is the key step in the formation of the six-membered piperidine ring. Further elaboration provides the target natural products 24, 34, and 37 in good overall yields.
Synthesis of β-<scp>d</scp>-Galactosyl Ceramide Methylene Isostere
The methylene isostere of the glycosphingolipid beta-D-galactosyl N-palmitoyl C-18 ceramide has been synthesized by a linear reaction sequence starting from a beta-linked D-galactopyranosyl aldehyde. First, this sugar aldehyde was converted into a methylenephosphorane which in turn was coupled with N-Boc serinal acetonide. The double bond of the resulting olefin was reduced and the oxazolidine ring was cleaved and oxidized to give a C-glycosyl N-Boc alpha-amino butanal (three-carbon chain elongation). Then, an additional C-15 carbon chain was installed by addition of lithium 1-pentadecyne to the above glycosyl amino aldehyde. The syn/anti ratio (70:30) of the resulting mixture of amino alcohols was reversed (5:95) by an oxidation-reduction sequence to achieve the same stereochemistry as in the hydrophilic head of D-erythro-sphingosines. The major product was subjected to the reduction of the triple bond with LiAlH4 to give the olefin with E geometry. Finally the N-amide group was installed by reaction with palmitoyl chloride and the O-benzyl protective groups of the sugar moiety were removed by treatment with lithium in liquid NH3-THF. The final product was characterized as the O-acetyl derivative.
A novel thermolytic annulation of an oxazolidinone: an enantiospecific synthesis of (-)-slaframine
作者:Mukund P. Sibi、James W. Christensen、Biqin Li、Paul A. Renhowe
DOI:10.1021/jo00042a002
日期:1992.7
Optically pure beta-aminopiperidines can be prepared in high yields through a thermolytic annulation sequence involving ring opening of an oxazolidinone.
Versatile synthesis of (+)-deoxypyridinoline, a biochemical marker for diagnosis of osteoporosis
作者:Maciej Adamczyk、Srinivasa Rao Akireddy、Rajarathnam E. Reddy
DOI:10.1016/s0957-4166(99)00329-8
日期:1999.8
A versatile chiral synthesis of the bone collagen cross-link, (+)-deoxypyridinoline (Dpd, 1) was described starting from a 3-hydroxypyridine derivative (2) via sequential introduction of three amino acid chains followed by hydrolysis. The key synthon 2, was prepared from vitamin B-6 (6). (C) 1999 Published by Elsevier Science Ltd. All rights reserved.