Novel, regioselective transformation of an oxirane system. An efficient approach to the synthesis of endocannabinoid 2-arachidonoylglycerol

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

“…[47] The important point of introducing a trifluoroacetyl functionality into a molecule is that it confers stability to the framework organization (e.g., prevents scrambling of acyl residues within the glycerol skeleton) and on this basis a convenient storage form for labile, biologically active glycerolipids has been proposed. [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.)…”

“…[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.…”

Direct Trifluoroacetylation Across a Trimethylsilyloxy System as a Stereo­specific, Chemo- and Regioselective Approach to C3-Vicinal Halohydrins

“…prevents migration of fatty acid residues within the glycerol skeleton) and thus such compounds can be considered as storage forms for labile, biologically important mono-or diacyl glycerols. 20 The added value of the trifluoroacetyl protection is that this group can be removed practically quantitatively under mild conditions, and the produced mono-or diglycerides usually do not require chromatographic purification. 20 So far, examples of direct transformation of various silyloxy systems (e.g.…”

“…20 The added value of the trifluoroacetyl protection is that this group can be removed practically quantitatively under mild conditions, and the produced mono-or diglycerides usually do not require chromatographic purification. 20 So far, examples of direct transformation of various silyloxy systems (e.g. trimethylsilyl-, tert-butyldimethylsilyl-, triisopropylsilyl-, tert-butyldiphenylsilyl ethers, etc.)…”