| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1987: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1986: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
When a tetraalkylammonium salt is treated with a strong base, a hydrogen atom alpha to the nitrogen is removed to give an ammonium ylide intermediate. Since usual ammonium salts contain different kinds of alpha-hydrogen atoms, different ylides may be formed simultaneously, and they are isomerized to the tertiary amines (Sommelet-Hauser and/or Stevens rearrangements), and also led to elimination of the alkyl group (Hofmann elimination). Thus the base-promoted ylide reactions usually give complex mixtures of tertiary amines.
We examined the fluoride-ion assisted desilylation of ammonium salts containing a N^+-CH_2-SiMe_3 group. N-(Substituted benzyl)trialkyl[(trimethylsilyl)methyl]ammonium halides reacted with cesium fluoride in HMPA or DMF at room temperature for about 20 h to give high yields of N,N-dialkyl-o-methylbenzylamines (Sommelet-Hauser rearrangement products).
A similar treatment of a cyclic ammonium compounds, 1-methyl-1-(trimethylsilyl)methyl-2-(substituted phenyl)piperiddinium bromides gave 9-ring cyclic amines, 2-methyl-1,3,4,5,6,11a-hexahy-dro-2H-2-benzazonine derivatives. Although these compounds are regarded as unstable intermediates in the Sommelet-Hauser rearrangement process, they were fairly stable in non-basic medium and could be used for further organic syntheses (e.g. for Diels-Alder reaction).
This ylide formation reaction can be applicable for the compounds having base-sensitive functional groups, and is useful for organic syntheses.
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