1995 Fiscal Year Final Research Report Summary
Development of Regio-and Stereoselective Wacker-type Oxidation and Its Synthetic Application
| Project/Area Number |
06650982
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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 |
有機工業化学
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| Research Institution | Osaka University |
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Principal Investigator |
HOSOKAWA Takahiro Osaka University, Dept.Chem., Associate Prof., 基礎工学部, 助教授 (90029520)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Allylic Compounds / hexamethylphosphoramide / Pd-Cu heterometallic complex / Asymmetric Acetalization / Isoxazolidines / 1beta-Methylcarbapenem |
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| Research Abstract |
In order to develop catalytic reactions highly controlled in terms of regio-and stereoselectivity, the following two subjects were investigated. (1) Regioselective oxygenation of terminal olefinic carbon in allylic compounds by the aid of Pd-Cu heterometallic catalyst and (2) Pd(II)-catalyzed, asymmetric acetalization of prochiral alkenes. The major results obtained in this study are as follows.
1.The C=C double bond of allylic compounds such as N-allylamides, N-allyllactams, and allylic esters was directly oxidized by molecular oxygen, when a catalyst system of PdCl_2(MeCN)_2 and CuCl was used together with hexamethyl-phosphoramide (HMPA) in non-aqueous solvents. The oxidation was found to be unique in terms of the regioselective production of aldehydes. This constitutes a sharp contrast with the usual Wacker oxidation which predominantly gives methyl ketones. The catalytic activity in the present oxidation was found to be improved by using Pd-Cu heterometallic complex bearing alkyl urea derivatives as the ligand.
2.Terminal olefinic carbon of N-methacryloyl-2-oxazolidinones is smoothly acetalized with alcohols in the presence of PdCl_2 catalyst. The use of (4S)-isopropyl, phenyl-, and tert-butyl-2-oxazolidinones as the chiral auxiliary results in the formation of the corresponding (2'S)-acetals in 61,80, and 95 %de, respectively. Reductive removal of the auxiliary with LiAlH4 followed by deacetalization products (R)-3-hydroxy-2-methylpropanal. The opposite enantiomer of this compound, derived from (4R)-substituted oxazolidinones, serves as a useful building block for synthesizing 1beta-methylcarbapenem precursor in high enantiomeric excess.
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