CARBENES .31. OXEPINES FROM PYRYLIUM-SALTS AND DIAZO ESTERS - CYCLOADDITION BEHAVIOR TOWARD 4-PHENYL-1,2,4-TRIAZOLINE-3,5-DIONE
CARBENES .31. OXEPINES FROM PYRYLIUM-SALTS AND DIAZO ESTERS - CYCLOADDITION BEHAVIOR TOWARD 4-PHENYL-1,2,4-TRIAZOLINE-3,5-DIONE
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DOI：
10.1021/jo00226a024
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发表时间：
1987-08-21
影响因子：
3.6
通讯作者：
REGITZ, M
中科院分区：
文献类型：
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作者：
HOFFMANN, KL;MAAS, G;REGITZ, M
结果4-（重氮甲基）-4-甲基-4H-吡喃8.通过报道的方法制备亲电重氮烷烃取代6所需的吡啶基-吡啶基盐6a;我们通过2，6-二苯基吡喃鎓高氯酸盐与甲基-由于重氮酯7a和B在乙醚中不与吡喃鎓盐6a和B反应，在三乙胺存在下（在这些条件下，在4-位上没有取代基的吡喃鎓盐易于被亲电重氮烷取代4），它们首先在1/1四氢呋喃/乙醚中在-115 ℃（7a）或-78 ℃（7 b）下在己烷中被丁基锂金属化（方案II）。
Results 4-(Diazomethyl)-4-methyl-4H-pyrans 8. The pyry-lium salt 6a required for the electrophilic diazoalkane substitution6 was prepared by reported methods; we have prepared the compound 6b in high yield (85%) by the reaction of 2, 6-diphenylpyrylium perchlorate with me-thylmagnesium iodide in ether followed by hydride cleavage using triphenylcarbenium tetrafluoroborate in acetonitrile.Since the diazo esters 7a and b did not react with the pyrylium salts 6a and b in the presence of triethylamine (pyrylium salts without substituents in the 4-position are readily susceptible to theelectrophilic diazoalkane sub-stitution under these conditions4), they were first meta-lated in 1/1 tetrahydrofuran/diethyl ether at-115 C (7a) or-78 C (7b) by butyllithium in hexane (Scheme II).