SYNTHESIS OF THE ENANTIOMERIC FUROBENZOFURANS, LATE PRECURSORS FOR THE SYNTHESIS OF (+)-AFLATOXINS AND (-)-AFLATOXINS B-1, B-2, G(1), AND G(2)
SYNTHESIS OF THE ENANTIOMERIC FUROBENZOFURANS, LATE PRECURSORS FOR THE SYNTHESIS OF (+)-AFLATOXINS AND (-)-AFLATOXINS B-1, B-2, G(1), AND G(2)
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DOI：
10.1021/jo00093a008
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发表时间：
1994-07-15
影响因子：
3.6
通讯作者：
RAPOPORT, H
中科院分区：
文献类型：
--
作者：
CIVITELLO, ER;RAPOPORT, H
对映体四氢呋喃并[2,3-b]苯并呋喃代表黄曲霉毒素 B-1、B-2、G(1) 和 G(2) 的 ABC 三环部分，由适当官能化的 O-芳基肟的 oxaza-Cope 重排生成。 O-芳基肟又由谷氨酸衍生的对映体纯醛和取代的苯氧胺缩合制成。通过电化学的使用，实现了 ABC 三环的 A 环取代基的高区域选择性。 4,6-双(甲苯磺酰氧基)-2-(甲氧基羰基)-2,3,3a,8a-四氢呋喃并[2,3-b]苯并呋喃 (22) 的区域选择性电化学裂解产生 97/3 的区域异构酚混合物。通过 2D NOESY NMR 确定所得酚的区域化学归属。通过对由31a与(+)-和(+/-)-苯乙胺偶联产生的非对映体进行NMR分析，确定最终产物的对映体比率为96/4。
Enantiomeric tetrahydrofuro[2,3-b]benzofurans, representing the ABC tricyclic portion of aflatoxins B-1, B-2, G(1), and G(2), were generated from the oxaza-Cope rearrangement of a suitably functionalized O-aryloxime. The O-aryloxime was, in turn, made from the condensation of an enantiomerically pure aldehyde derived from glutamic acid and a substituted phenoxyamine. High regioselectivity with respect to the A-ring substituents of the ABC tricycle was achieved through the use of electrochemistry. The regioselective electrochemical cleavage of 4,6-bis(tosyloxy)-2-(methoxycarbonyl)-2,3,3a,8a-tetrahydrofuro[2,3-b]benzofuran (22) resulted in a 97/3 mixture of regioisomeric phenols. The regiochemical assignments of the resulting phenols were determined by 2D NOESY NMR. The enantiomeric ratio of the final product was determined to be 96/4 by NMR analysis of diastereomers resulting from the coupling of 31a to (+)- and (+/-)-phenethylamine.