在存在CuCN的情况下,通过用锆茂茂-丁烯配合物处理原丙烯酸三乙酯与烯丙基和炔丙基磷酸酯在高S N 2'中在4的α位进行原位生成的γ,γ-二烷氧基烯丙基锆物种4的反应。选择性地分别得到相应的5-链烯酸酯和4,5-链二烯酸酯。在当前的Cu(I)介导的偶联反应中,γ,γ-二烷氧基烯丙基锆物种4用作丙酸酯的合成有用的均烯酸酯阴离子当量。
Ether-directed diastereoselectivity in catalysed Overman rearrangement: comparative studies of metal catalysts
摘要:
Ether-directed diastereoselectivity in Overman rearrangement of delta-methoxy and delta-TBDMSO substituted allylic trichloroacetimidates has been explored using PtCl2, PtCl4, AuCl and AuCl3 catalysts in comparison with commonly used Pd(II) catalysts. For both substrates the use of PtCl2 catalyst gave notably improved anti/syn-ratio of 1,2-aminoalcohol derivatives (anti/syn=11:1 for 5-methoxy; 6:1 for delta-TBDMSO) compared to all metal catalysts known to promote Overman rearrangement. Formation of 2-trichloromethyloxazoline was observed as a dominant side reaction in the metal catalysed rearrangement of a-methoxy substituted allylic trichloroacetimidates considerably reducing the yield of the desired product. This side reaction was suppressed when delta-TBDMS-ether was used as a directing group. (C) 2008 Elsevier Ltd. All rights reserved.