Regioselective opening of an oxirane system with trifluoroacetic anhydride. A general method for the synthesis of 2-monoacyl- and 1,3-symmetrical triacylglycerols

Occurrence of 3-MCPD and glycidyl esters in edible oils in the United States

“…(1-Pa-d5) were (CAS 7460-84-6) were synthesised according to a literature procedure (Stamatov & Stawinski 2005); all their structures were confirmed by 1 H-NMR with purities greater than 95%. 3-MCPD di-ester standards, synthesised according to a published procedure (Haines et al 2011) were generously donated by the Archer Daniels Midland Co. (Decatur, IL, USA).…”

Regioselective and Stereospecific Halosilylating Cleavage of the Oxirane System of Glycidol Derivatives as an Efficient Strategy to C2‐O‐Functionalized C3‐Vicinal Halohydrins

“…1 .11, CHCl 3 )] were prepared by acylation of chiral glycidols with oleoyl chloride (all from Fluka) as described elsewhere. [49] (rac)-(Ϯ)-2-(Hexadecyloxymethyl)oxirane (3) (white solid, m.p. 34.0-35.1°C) was obtained from racemic glycidyl tosylate (Fluka) in two steps by following a standard approach.…”

“…[58] No attempts were made to optimize these particular procedures that provided glycidyl substrates 1-3 with spectral and physicochemical characteristics comparable to those reported in the literature. [49,58] …”

“…[48] The added value of the trifluoroacetyl protection is that this group can be removed quantitatively under mild conditions to provide pure target compounds without any additional workup or chromatographic purification. [48,49] Examples of a direct conversion of various silyloxy systems (e.g., trimethylsilyl-, tert-butyldimethylsilyl-, triisopropylsilyl-, tert-butyldiphenylsilyl ethers, etc.) into either acetates (e.g., by using FeCl 3 -acetic anhydride, [50] pyridineacetic anhydride-acetic acid, methanol-acetic acid, [51] ZnCl 2 -acetyl chloride, [52] or SnBr 2 -acetyl bromide [53] ) or higher carboxylates [54] are known from the literature.…”

“…As part of our program on new synthetic approaches to glycerolipids, [48,49,55] we developed recently a three-compo- Scheme 7. nent system, namely Bu 4 NBr-TMSBr-carboxylic acid anhydrides, that efficiently effected replacement of silyl transient protections by short-or long-chain acyl residues directly. [54] Although utility of this reagent can be extended to the production of vicinal bromoesters, it appeared to be less suitable for the synthesis of C2-O-acylated C3-vicinal chloro-and iodohydrins from the corresponding O-trimethylsilyl congeners (e.g., type 4 and 8, Scheme 6) as a result of the competitive formation of bromohydrin byproducts (ca.…”