| Budget Amount *help |
¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1997: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1996: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Research Abstract |
The aldol type reaction of phenolic enolate of methyl 2,4-dihydroxybenzoate (1) with aldehydes in methanol was accomplishied using alkaline earth metal reagents such as Ca (OH) _2, Ba (OH) _2, CaCl_2/KOH,or BaCl_2/KOH instead of alkaline metal reagents such as NaOH,KOH,LiCl/KOH or NaCl/KOH.The C-C bond formation was regioselectively performaed at the C (3) position of benzoate 1. When the reaction of 1,3-dihydroxyacetone (2) with formaldehyde was promoted by CaCl_2/KOH in methanol, the aldolcondensation between formaldehyde and 2 without protection of the hydroxy groups gave glycerotetrulose (3) and 3-pentulose (4). In contrast, this reaction carried out in water mainly gave 1-hydroxy-2,3-butanedione (5). Formation of 5 means that the dehydration of 3 is accelerated in water. Utilization of amines as a basic catalyst in water also promoted the dehydration of 3 to afford 5.
The sequence described above was successfully applied to the stereoselective synthesis of threo-4 from glycero-tetrulose (3) and formaldehyde. Combination of SmCl_3 with KOH perfomed this *nsformation with the higher threo selectivity.
In comparison with (CH_2O) _n which is soluble in water, we chose a hydrophobic aldehyde, benzaldehyde, whose proportion of the hydrate form is low. 1,3-Dihydroxyacetone (2) is soluble in water and easily form cyclic dimers which contain hemiacetal groups in stead of the carbonyl group. Therefore, when 2 and benzaldehyde were treated with Ca (OH) _2 or CaCl_2/KOH in methanol, the enolate of 2 reacted not with another dihydroxyacetone molecule but with benzaldehyde to yield threo-rich 4-C-phenyl glycero-tetrulose. In the case of the reaction of 2 with methyl vinyl ketone, 4-acetyl-2,3,4,5-tetrahydro-3-hydroxy-3- (hydroxymethyl) furan was produced by the hetero 1,4-addition reaction followed by intramolecular aldol-type cyclization.
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