1994 Fiscal Year Final Research Report Summary
Asymmetric Synthesis using Enantiomerically Defined alpha-Oxystannanes
| Project/Area Number |
05453136
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Synthetic chemistry
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
NAKAI Takeshi Tokyo Inst.Tech., Fac. Eng., Prof., 工学部, 教授 (90016717)
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| Co-Investigator(Kenkyū-buntansha) |
TOMOOKA Katsuhiko same as above Res. Assoc., 工学部, 助手 (70207629)
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| Project Period (FY) |
1993 – 1994
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| Keywords | Enantiomerically defined alpha-oxystannanes / Asymmetric synthesis / Carboanion reaction / Asymmetric [2,3] -Wittig rearrangement / Asymmetric [1,2] -Wittig rearrangement / Asymmetric carbolithiative cyclization |
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| Research Abstract |
The purpose of this work is to develop the new method for asymmetric synthesis using enantiomerically defined alpha-oxystannanes. A summary of the research results is as follow :
(1) A new practical method for asymmetric synthesis of alpha-hydroxystannanes
The TiCl_4-promoted reaction of (4S,6S) - (4,6-dimethyl-1,3-dioxan-2-yl) tributylstannane with Grignard reagents is shown to sfford, after oxidation followed by base treatment, the (S) -alpha-hydroxystannanes in >95-20% ee.
(2) Asymmetric [2,3] -Wittig rearrangement
The [2,3] -Wittig rearrangement of enantiomerically-defined alpha- (allyloxy) stannanes, prepared from (S) -1-tributylstannyl-1-propanol, with butyllithium is shown to proceed with essentially complete inversion of configuration at the Li-bearing migrating terminus.
(3) Asymmetric [1,2] -Wittig rearrangement
The [1,2] -Wittig rearrangements of enantio-defined alpha-benzyloxypropyllithium and its (R) -alpha-methylbenzyloxy analogs, generated from the enantio-enriched stannanes via Sn/Li exchange, are shown to proceed predominantly with inversion of configuration at the Li-bearing terminus and retention of configuration at the migrating center, and exhibit a significant level of mutual enantiomer recognition in the radical recombination process.
(4) Asymmetric carbolithiative cyclization
The carbolithiative cyclization of enantiomerically-defined alpha-(homoallyloxy)stannane, with butyllithium is shown to proceed with complete retention of configuration at the Li-bearing center.
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Research Products
(14 results)
