Syntheses of (1S,2S,3S,4R)- and (1R,2R,3S,4R)-2,3,4-trihydroxycyclopentane-1-methanol, carbocyclic analogs of .alpha.-L-arabinofuranose and .beta.-D-ribofuranose
A Convenient Approach for Access to Both Carbapentofuranoses and Carbahexopyranoses. Stereocontrolled Synthesis of Enantiopure Carba-<scp>d</scp>-ribofuranoses, Carba-<scp>d</scp>-arabinofuranoses and Carba-<scp>l</scp>-gulopyranose
key step involves ring-closing metathesis of dienols 6 derived from a (R)-(+)-glyceraldehyde derivative 4 to form the substituted cyclopentenol 9 and cyclohexenol 34a. Stereocontrolled addition of hydroxyl groups followed by conversion of the ketal unit to hydroxymethyl group in these intermediates led to carbapentoses and -hexoses. Stereoselectivity during introduction of hydroxyl groups arises through
报道了一种对映体纯净形式的Carcarbugars的新方法。关键步骤涉及衍生自(R)-(+)-甘油醛衍生物4的二烯醇6的闭环易位,以形成取代的环戊烯醇9和环己烯醇34a。在这些中间体中立体控制地添加羟基,然后将缩酮单元转化为羟甲基,导致产生碳戊糖和-己糖。在引入羟基的过程中,立体选择性是由烯丙基取代基构成的位阻引起的。本方法的显着特征是d-和l的可访问性系列的羧甲基戊糖,分别由β- d-和β- 1-碳氢呋喃呋喃糖酶17和20的合成说明。卡巴-α- d -ribofuranose 25,生物合成中间对抗生素芒霉素,也被从相同的环戊烯醇合成9。环戊烯醇9a中的官能团操纵也使能够获得呋喃糖呋喃糖32。本合成策略可以延长carbahexopyranose的合成,由卡巴-β-的合成如图升-gulopyranose 40B。
Variable Strategy toward Carbasugars and Relatives. 2.<sup>1</sup> Diversity-Based Synthesis of β-<scp>d</scp>-Xylo, β-<scp>d</scp>-Ribo, β-<scp>l</scp>-Arabino, and β-<scp>l</scp>-Lyxo 4a-Carbafuranoses and (4a-Carbafuranosyl)thiols
The silyloxy diene-based construction of carbasugars, previously exploited for the synthesis of four carbocyclic furanose and pyranose analogues, has been investigated further. By introducing a novel silylative cycloaldolization protocol and by adjusting a couple of minor transformations, the efficiency of this synthetic sequence was greatly improved. Through a series of lactone/thiolactone aldehyde cyclization precursors, four carbafuranoses (4a-carba-beta -D-xylofuranose, 4a-carba-beta -D-ribofuranose, 4a-carba-beta -L-arabinofuranose, and 4a-carba-beta -L-lyxofuranose) and four (carbafuranosyl)thiols [(4a-carba-beta -D-xylofuranosyl)thiol, (4a-carba-beta -D-ribofuranosyl)thiol, (4a-carba-beta -L-arabinofuranosyl)thiol, and (4a-carba-beta -L-lyxofuranosyl)thiol] were assembled. From this study, it was shown that these constructions tolerate a variety of precursors, and in many instances, they are suitable for scaling-up.
Stereoselective synthesis of a novel natural carbasugar and analogues from hydroxymethylated cycloalkenone scaffolds
Novel carbasugars from Streptomyces lincolnensis have been synthesized from an enantiomerically pure 5-hydroxymethyl-cyclohex-2-enone scaffold via a stereoselective approach. Several structural analogues of those carbasugars have also been synthesized in a stereoselective manner from hydroxymethylated cycloalkenone derivatives. (C) 2012 Elsevier Ltd. All rights reserved.
MARSCHNER, CHRISTOPH;PENN, GERHARD;GRIENGL, HERFRIED, TETRAHEDRON LETT., 31,(1990) N0, C. 2873-2874