DIASTEREOSELECTIVITY IN THE LATERAL METALATION AND ELECTROPHILIC QUENCHING OF ISOXAZOLYLOXAZOLINES
DIASTEREOSELECTIVITY IN THE LATERAL METALATION AND ELECTROPHILIC QUENCHING OF ISOXAZOLYLOXAZOLINES
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DOI：
10.1021/jo00049a039
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发表时间：
1992-11-06
影响因子：
3.6
通讯作者：
NATALE, NR
中科院分区：
文献类型：
--
作者：
MIRZAEI, YR;SIMPSON, BM;NATALE, NR
在大多数情况下，异恶唑的C-5位上的手性异恶唑啉的金属化和亲电猝灭导致适度的非对映选择性。一般来说，4(S)-(甲氧甲基)-5(S)-苯基-2-恶唑啉助剂(迈耶试剂)在主要非对映异构体的C-5异恶唑位置产生S的绝对构型，优先考虑异恶唑；EL>；R>；H。异恶唑烷类化合物3可以被选择性地脱保护，生成异恶唑烷醛4和4-异恶唑基-1，4-二氢吡啶5。5的固体构象是关于杂环连接的O-endo和关于3，5-二酯基的sp，sp。IDHP 5的(+)对映体能有效地将H-3标记的1，4-二氢吡啶从心肌细胞膜上的钙通道中置换出来。
Metalation and electrophilic quenching of chiral isoxazolyloxazolines at the C-5 position of the isoxazole gives rise to modest diastereoselectivity in most cases. In general, the 4(S)-(methoxymethyl)-5(S)-phenyl-2-oxazoline auxilliary (Meyer's reagent) produces the S absolute configuration at the C-5 isoxazole position of the major diastereomer, for priorities isoxazole > El > R > H. The enantiomerically pure isoxazolyloxazolines 3 can be obtained by preparative HPLC. The isoxazolyloxazolines 3 can be deprotected selectively to produce isoxazolecarboxaldehyde 4, and 4-isoxazolyl-1,4-dihydropyridine 5. The solid-state conformation of 5 is O-endo with respect to the ring juncture between the heterocyclic rings and sp, sp with respect to the 3,5-diester groups. The (+) enantiomer of IDHP 5 proved to be 2 orders of magnitude more effective in the displacement of H-3-labeled 1,4-dihydropyridine from Ca2+ channels in cardiac membranes.