Simple Method for the Preparation of Esters from Grignard Reagents and Alkyl 1-Imidazolecarboxylates

Abstract

The reaction of Grignard reagents with alkyl imidazolecarboxylates, which were prepared from alcohols with carbonyl diimidazole, gave the corresponding esters in good to excellent yields. This method conveniently provides esters from alkyl halides and alcohols by C1-carbon chain extension.

Hyaluronan derivatives bearing variable densities of ferulic acid residues

“…The spectroscopic ( 1 H and 13 C-NMR spectra) features of this compound were in agreement with those described in the literature. 12,13 The same ash chromatography purication of the reaction mixture with dichloromethane-ethyl acetate (1 : 2) as the eluent afforded compound 2 as a pale yellow oil, which crystallized spontaneously to form a whitish yellow solid (0.027 g, yield 37%).…”

Diazo Preparation via Dehydrogenation of Hydrazones with “Activated” DMSO

“…Upon completion of the reaction the mixture was diluted with Et 2 O (75 mL), washed with saturated aq. NaHCO 3 (2×50 mL), brine (50 mL), dried with Na 2 SO 4 , and concentrated in vacuo to give the desired ester which could be further purified by flash column chromatography (pentane and EtOAc 90:10); Diphenylmethyl benzoate (88% yield; rf: 0.58), 5 benzyl benzoate (75% yield; rf: 0.50), 6 1-phenylethyl benzoate (61% yield; rf: 0.52), 6 and cyclohexyl benzoate (4% yield; rf: 0.44) 7 had characterization data identical to published values. The procedure used to quantitate the gas evolved during acid catalyzed diazo decomposition was based on the methods described by Holton, McGuiness and Shechter.…”

Chelation-Based Homologation by Reaction of Organometallic Reagents with O-Alkyl S-Pyridin-2-yl Thiocarbonates: Synthesis of Esters from Grignard Reagents

“…1,2 To eliminate this complexity, two categories of one-step method for the preparation of esters from Grignard reagents have been explored (Scheme 1). The first is the use of an alkoxycarbonyl donor having regulated leaving activity, such as an alkoxycarbonyl phosphonium salt, 3 a 1-(alkoxycarbonyl)pyrazole, 4 or a 1-(alkoxycarbonyl)imidazole, 5 to form a tetrahedral intermediate (Scheme 1, Equation 1). The other is the use of an alkyl chloroformate with an organometallic compound having a regulated nucleophilicity, such as a powdered Grignard reagent chelated with tris[2-(2-methoxyethoxy)ethyl]amine (TDA-1) 6 or an organocopper reagent derived from a Grignard reagent, 7 to avoid overreaction of the ester product (Scheme 1, Equation 2).…”