期刊
JOURNAL OF ORGANIC CHEMISTRY
卷 78, 期 12, 页码 6182-6195出版社
AMER CHEMICAL SOC
DOI: 10.1021/jo400858u
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资金
- Ministry of Education, Science and Culture of Japan [20550094, 20200052, 24550116]
- Grants-in-Aid for Scientific Research [20200052, 24550116, 20550094] Funding Source: KAKEN
The effects of including metal salts for three. component reactions involving alpha-alkyl-alpha-diazo esters, aromatic aldehydes, and 3-(2-alkenoyl)-2-oxazolidinones are described, in terms of yields and diastereoselectivities. Metal tetrafluorborates (10-30 mol %) such as Co(BF4)(2)center dot 6H(2)O, Ni(BF4)(2)center dot 6H(2)O, and AgBF4 were effective in delivering high yields and diastereoselectivities (93:7 to 99:1) of the corresponding tetrahydrofuran derivatives while suppressing the competitive formation of 1,3-dioxolane. Using (S)-3-(2-alkenoyl)-4-isopropyl-2-oxazolidinones as the dipolarophiles in the three-component reactions, in the presence of Ni(BF4)(2)center dot 6H(2)O or Co(ClO4)(2)center dot 6H(2)O (10-30 mol %), optically active tetrahydrofurans that possess four successive asymmetric centers were synthesized in high diastereoselectivities (99:1). On the basis of the configuration of the cycloadduct using the X-ray analysis, the high diastereoselectivity could be explained by the unusual Re-face approach to the dipolarophile in the presence of the Lewis acid, proceeding through the s-cis conformer of the 3-(2-alkenoyl)-2-oxazolidinone with the two carbonyls in opposing directions (dipole-dipole interaction).
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