Esterification with propionyl chloride

An electrophilic addition of chloroform to SWNTs was followed by hydrolysis and it resulted in the addition of hydroxyl groups to the surface of the nanotubes. Its esterification with propionyl chloride led to the corresponding ester derivatives (Tagmatarchis et al., 2002). 

In total synthesis of the structurally unique natural product calcimycin (15), Grieco and others used Ireland-Claisen rearrangement of the ester 17 to synthesize the key intermediate (18)7 (Scheme 1.3g). Monosilylation of the diol 16 followed by treatment with propionyl chloride in pyridine gave rise to the ester 17 in 90% yield. Treatment of 17 with LDA in THF at —78 C, subsequent addition of ferf-butyldimethylsilyl chloride in HMPA, and brief heating of the resulting silylketene acetal provided the corresponding silyl ester. Subsequent hydrolysis of the silyl ester and esterification with diazomethane gave 18 in 90% yield from 17. 

The Ireland contribution to nonactic acid synthesis, outlined in Scheme 4.32, involves a selective silyl ketene acetal formation and Claisen rearrangement in the key step. D-Mannose (209) was readily converted in a straightforward manner to dihydrofuran 212 via 210 and 211 in 36% overall yield. Esterification of the free alcohol with propionyl chloride followed by the an enolate Claisen rearrangement afforded a mixture (89 11) of tetrahydrofuryl propionates 213 after catalytic reduction. 

Gray s group also prepared the propanoate of (2-hydroxypropyl)cellulose (PPC or C3PC) from the esterification reaction of HPC (Mw = 100,000 g/mol) and propionyl chloride or propionic anhydride in acetone (Tseng et al. 1982). The appearance and behavior of the polymer is similar to APC, however this ester displayed iridescent colors at room temperature. In the same year (Bhadani and Gray 1982), the synthesis of the benzoic acid ester of HPC (BzPC) from the reaction of the aromatic benzoyl chloride with HPC in pyridine was described. The polymer showed a thermotropic liquid crystalline phase below 160 °C. Benzoic acid ester of HPC was fractionated from acetone solution by precipitation with methanol-water and polymers with different molecular weights were obtained (Bhadani et al. 1983). 

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