Esterification valeric acid

Promotion of Lipase-Catalyzed Esterification of N-Valeric Acid and Citro-neUol in Supercritical Carbon Dioxide in the Near-Critical Region (Ikushima et al 1996). 

The first synthesis of rfZ-deoxynupharidine was reported by Kotake et al. (30). The starting material w as 2,5-lutidine which was made to react with formaldehyde to give the diol XXVII on dehydration, acetylation, and condensation with malonic ester XXVII afforded the diester XXVIII. On hydrogenation and acid hydrolysis XXVIII was decarboxylated to the valeric acid derivative XXIX. After esterification the acid was acylated with 3-furoyl chloride and distilled with soda lime to yield dehydrodeoxynupharidine (XXX), and this on hydrogenation gave dl-deoxynupharidine (II). 

In the case of ester derivatives the degree of esterification (i.e., mono or diesters) and the size of the esterifying acid helps to determine the extent of lipophilicity of the product. Thus betamethasone 17-valerate (Table 14-1) would be expected to be more soluble in CHC13 (1 2) than the 21 -acetate (1 16), which in turn is more lipid soluble than the alcohol (1 325). Topical antiinflammatory potency parallels such values. 

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