581784-60-3Relevant academic research and scientific papers
Parallel synthesis of an ester library for substrate mapping of esterases and lipases
Morley, Krista L.,Magloire, Vladimir P.,Guerard, Christine,Kazlauskas, Romas J.
, p. 3005 - 3009 (2007/10/03)
Use of solid-supported reagents simplified routine acylation of primary and secondary alcohols because it eliminated traditional purification. Using a parallel synthesizer, eight primary or secondary alcohols reacted with acid chloride in the presence of poly(4-vinylpyridine), which acted as a base and acylation catalyst. Filtration, subsequent addition of amino-functionalized silica gel to remove excess acid chloride and a second filtration affording the corresponding esters in high yield (70-98%), excellent chemical purity (93-99%). Acylation of enantiopure alcohols yielded enantiopure esters. Acylation of two tertiary alcohols gave esters in low yield (27-57%) and variable chemical purity (57-99%).
Reductions of carboxylic acids and esters with NaBH4 in diglyme at 162°C
Zhu, Hua-Jie,Pittman Jr., Charles U.
, p. 1733 - 1750 (2007/10/03)
Aromatic esters, including the extremely sterically hindered ester: tamyl 2-chlorobenzoate, are readily reduced to the corresponding benzyl alcohols in high yield with NaBH4 in refluxing diglyme (162°C). In sharp contrast, aliphatic esters usually gave only low yields of alcohols. Instead, diglyme fragmentation products are formed which undergo transesterification reactions, producing complex product mixtures including products such as RCOOCH2CH2OCH3. The mechanism of this process involves sodium borohydride-induced SN2 cleavage of diglyme (hydride attack) at high temperatures. However, when the extremely electron rich, 3,4,5-trimethoxybenzoic acid is treated with NaBH4/diglyme at 162°C (with or without an equivalent of LiCl), no 3,4,5-trimethyoxybenzyl alcohol is formed. The electron rich and hindered ester, t-amyl-3,4,5-trimethoxybenzoate, also does not reduce under these conditions (with or without LiCl). However, both methyl and isopropyl 3,4,5-trimethoxybenzoate esters were converted into 3,4,5-trimethyoxybenzyl alcohol in good yields in NaBH4/diglyme/LiCl at 162°C. These reductions did not occur unless LiCl was present, illustrating the electron releasing effect of the three methoxy functions which reduce the carbonyl group's reactivity.
