‘Hidden’ axial chirality as a stereodirecting element in reactions involving enol(ate) intermediates. Part 2.† Cyclisation reactions of methyl (4R)-3-(2-diazo-3-oxobutanoyl)-1,1-dioxo-1λ6,3- (and 1-oxo-1λ4,3-) thiazolidine-4-carboxylates
‘Hidden’ axial chirality as a stereodirecting element in reactions involving enol(ate) intermediates. Part 2.† Cyclisation reactions of methyl (4R)-3-(2-diazo-3-oxobutanoyl)-1,1-dioxo-1λ6,3- (and 1-oxo-1λ4,3-) thiazolidine-4-carboxylates
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“隐藏”轴向手性作为涉及烯醇（酸酯）中间体的反应中的立体定向元件第 2 部分。† 甲基 (4R)-3-(2-重氮基-3-氧代丁酰基)-1,1-二氧代-1λ6 的环化反应， 3-（和1-氧代-1λ4,3-）噻唑烷-4-羧酸酯
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
S. Vohra
中科院分区：
文献类型：
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作者：
M. J. Betts;R. Pritchard;A. Schofield;R. J. Stoodley;S. Vohra
（4 R）-3-（2-重氮-3-氧代丁酰基）-1，1-二氧代-1 6，3-噻唑烷-4-羧酸甲酯14经过碱诱导的环化反应，得到高对映体纯度状态的（8aS）-3-乙酰基-4，7，7-三氧代-1，4，6，7，8，8a-六氢-7 6-[1，3]噻唑并[4，3-c][1，2，4]三嗪-8a-羧酸甲酯15。用（1 R，4 R）-和（1 S，4 R）-3-（2-重氮基-3-氧代丁酰基）-1-氧代-1 λ 4，3-噻唑烷-4-羧酸甲酯25和27观察到类似的立体选择性环化，继续保持构型，得到化合物33和34。双环砜15和双环亚砜33和34也是由甲基（8aS）-3-乙酰基-4-氧代-1，4，8，8a-四氢[1，3]噻唑并[4，3-c][1，2，4]三嗪-8a-羧酸酯5与间氯过氧苯甲酸（在砜15的情况下在DMF中，在亚砜33和34的情况下在CHCl 3中）。在甲醇中使用氧化剂或在甲酸中使用过氧化氢导致氧化脱乙酰化，得到（8aS）-3，4，7，7-四氧代全氢-7 λ6-[1，3]噻唑并[4，3-c][1，2，4]三嗪-8a-羧酸甲酯17，其结构通过X射线晶体学分析确定。分析揭示了一个有趣的包装安排的分子在晶体中，归因于一个分子间氢键网络。特别地，酯羰基氧原子和1位的氨基氢原子之间的分子间氢键为化合物17的固态IR光谱中酯羰基吸收向1680 cm-1的位移提供了可能的解释。
Methyl (4R)-3-(2-diazo-3-oxobutanoyl)-1,1-dioxo-1λ6,3-thiazolidine-4-carboxylate 14 undergoes a base-induced cyclisation to give methyl (8aS)-3-acetyl-4,7,7-trioxo-1,4,6,7,8,8a-hexahydro-7λ6-[1,3]thiazolo[4,3-c][1,2,4]triazine-8a-carboxylate 15 in a state of high enantiomeric purity. Similar stereoselective cyclisations, proceeding with retention of configuration, are observed with methyl (1R,4R)- and (1S,4R)-3-(2-diazo-3-oxobutanoyl)-1-oxo-1λ4,3-thiazolidine-4-carboxylates 25 and 27 to give compounds 33 and 34. It is suggested that the cyclisation reactions proceed by way of planar ester enol(ate) intermediates which possess axial chirality, e.g. 35.The bicyclic sulfone 15 and the bicyclic sulfoxides 33 and 34 are also produced by oxidation of methyl (8aS)-3-acetyl-4-oxo-1,4,8,8a-tetrahydro[1,3]thiazolo[4,3-c][1,2,4]triazine-8a-carboxylate 5 with m-chloroperoxybenzoic acid (in DMF in the case of the sulfone 15 and in CHCl3 in the case of the sulfoxides 33 and 34). The use of the oxidant in methanol or of hydrogen peroxide in formic acid leads to an oxidative deacetylation to give methyl (8aS)-3,4,7,7-tetraoxoperhydro-7λ6-[1,3]thiazolo[4,3-c][1,2,4]triazine-8a-carboxylate 17, the structure of which is established by an X-ray crystallographic analysis. The analysis reveals an interesting packing arrangement of the molecules in the crystal, attributable to an intermolecular H-bonding network. In particular, intermolecular H-bonding between the ester carbonyl oxygen atom and the amino hydrogen atom at position 1 provides a possible explanation for the shift of the ester carbonyl absorption to 1680 cm–1 in the solid-state IR spectrum of compound 17.