1991 Fiscal Year Final Research Report Summary
1-Methoxy-3-Phenylthiopropene ; Utilization as a propenal anion equivalent
| Project/Area Number |
02453097
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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 | Okayama University of Science |
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Principal Investigator |
NOZAKI Hitosi Okayama Univ. Sci. Fac. Eng. Professor, 工学部, 教授 (40025763)
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| Co-Investigator(Kenkyū-buntansha) |
SATO Tsuneo Okayama Univ. Sci. Fac. Eng. Lecturer, 工学部, 講師 (80183383)
OTERA Junzo Okayama Univ. Sci. Fac. Eng. Professor, 工学部, 教授 (20131617)
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| Project Period (FY) |
1990 – 1991
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| Keywords | 1-methoxy-3-phenylthiomethane / [2, 3]sigmatropy / enal / shydroxy-alpha-enal / チオスタンナン / αーエナ-ルアセタ-ル / アリル陰イオン / 位置選択性 |
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| Research Abstract |
Exposure of propenal acetals, CH_2=CHCH(OR)_2 to thiostannanes in the presence of Lewis acid affords PhSCH_2CH=CH(OR). These compounds undergo lithiation at the PhS group-bearing carbon. The carbanions thus formed react with various electrophiles on the same carbon. Conversion of these sulfides into the corresponding sulfoxides followed by[2, 3]sigmatropy provides the desired enals, ECH=CHCHO. As a result of these transformations, an electrophile is introduced on the 3-position of propen-al and hence the reagent, LiCH(SPh)CH=CHO, is regarded as an anion equivalent of propenals. One of the notable features of the present transformation is the high regioselectivity with which electrophile is always incorporated at the 3-position. Moreover, it is synthetically important that the[2, 3]sigmatropic reaction gives rise to enals ECH=CHCHO with high E-stereochemistry. The same high stereoselectivity holds for trisubstituted carbon-carbon double bond and quite surprisingly, even for tetrasubstituted ones. This is the first example of such high stereoselection in the Mislow-Evans rearrangement. The reaction is controlled by the bulky group which occupies at the pseudo equatorial position in the five-membered cyclic transition state.
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