1994 Fiscal Year Final Research Report Summary
Asymmetric synthesis by alkylation of alpha, beta-unsaturated aldehyde hydrazones
| Project/Area Number |
05650887
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Synthetic chemistry
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| Research Institution | Doshisha University, Faculty of Engineering |
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Principal Investigator |
YAMASHITA Masakazu Doshisha Univ., Fac. Eegineering, Professor, 工学部, 教授 (20113102)
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| Project Period (FY) |
1993 – 1994
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| Keywords | Asymmetric carbon / Hydrazones / Asymmetric synthesis / Alkylation / Aldehydes / Nitriles |
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| Research Abstract |
Enantio-and regioselective alkylation of alpha, beta-unsaturated aldehyed hydrazones or imines to alpha-alkyl-beta, gamma-unsaturated carbonyl compounds are described.
2-Alkyl-2-methyl-3-butenal which has quaternary carbon atom at alpha-position was synthesized from 2-methyl-2-butenal cyclohexylimine by successive deprotonation by base, alkylation, and the following hydrolysis. This shows that alkylation occurred at alpha-position selectively and the alpha, beta-unsaturated double bond migrated to beta, gamma.
Similar results were obtained using hydrazone derivatives such as dimethylhydrazones instead of cyclohexylimines. 2-Alkyl-2-methyl-3-butenal was obtained from these dimethylhydrazones by hydrolysis with copper (II) choride. When magnesium mono-peroxyphthalate was used, 2-methyl-2-butenonitrile which has quaternary carbon atom at alpha-position were produced from these dimethylhydrazones in good yields.
When chiral hydrazones such as 2-methyl-2-butenal SAMP ( (S) -1-amino-2- (methoxymethyl) pyrrolidine) hydrazone were used, chiral nitriles were produced in good enantioselectivity. The absolute configuration of (-) -2-benzyl-2-methyl-3-butenonitrile was elucidated as (R) -series by chemical correlation with (S) - (+) -methyl 2-cyano-2-methyl-3-phenylpropionate, whose absolute configuration is already established.
Moreover, chiral aldehydes which have asymmetric quaternary carbon atom at alpha-position were produced in moderate enantioselectivity when chiral imines such as 2-methly-2-butenal (S,S) -ADPD ( (4S,5S) - (+) -5-amino-2,2-dimethyl-4-phenyl-1,3-dioxane) imine were used.
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