1,1-Diacyloxy-1-phenylmethanes as versatile N-acylating agents for amines

Amine Activation: “Inverse” Dipeptide Synthesis and Amide Function Formation through Activated Amino Compounds

“…The analytical data were identical in all respects to those previously reported in the literature. 49 Methyl 3-(5-oxo-5-phenylpentanamido)propanoate (20q). Purification by flash column chromatography on silica gel eluting with pentane/ethyl acetate mixture (7:3 to 2:3, v/v) afforded the title compound as a white solid (106 mg, 76%).…”

Recent Advances in Cross-Couplings of Functionalized Organozinc Reagents

“…7 These geminated diacetates like 1a were readily prepared from the corresponding aldehyde (7a) and acetic anhydride. 8 Thus, an excess of PhZnCl•MgCl2 (8a) prepared from the corresponding arylmagnesium reagent reacted with 1a in THF at 80 °C providing the double cross-coupling product, e.g. the triarylmethane 9a in 81% yield.…”

“…7 Geminated diacetates such as 1a were readily prepared from the corresponding aldehyde (7a) and acetic anhydride. 8 Thus, an excess of PhZnCl•MgCl 2 (8a), prepared from the corresponding arylmagnesium reagent, reacted with 1a in THF at 80 °C, providing the double cross-coupling product, namely, the triarylmethane 9a, in 81% yield. Alternatively, by using only 1.0 equiv of PhZn-Cl•MgCl 2 (8a) under milder reaction conditions (25 °C, 12 h or 60 °C, 3 h), a mono-substitution reaction was possible, leading to the benzhydryl acetate 10a in 86% yield.…”

Selective Synthesis of Acylated Cross-Benzoins from Acylals and Aldehydes via N-Heterocyclic Carbene Catalysis

“…Oxonium intermediates derived from acylals behave as electrophiles in reactions such as the Hosomi−Sakurai allylation, 12 and acylals have also been applied in the selective protection of formyl groups in the presence of keto groups 13 and as reagents for acetylation under mild conditions. 14 Although they are readily accessible from aldehydes in one step 15 and are relatively reactive, acylals have not been fully utilized as building blocks in organic synthesis. Herein, we report the use of acylals as aldehyde equivalents for the chemoselective cross-benzoin reaction catalyzed by NHCs to afford O-acyl-protected benzoins.…”

“…In our search for an aldehyde equivalent for the chemoselective cross-benzoin reaction, the reactivity of acylals inspired us to hypothesize that oxonium intermediates, presumably generated from acylals by dissociation of an acyloxyl group, would react with Breslow intermediates, the key intermediates for benzoin reaction. Oxonium intermediates derived from acylals behave as electrophiles in reactions such as the Hosomi–Sakurai allylation, and acylals have also been applied in the selective protection of formyl groups in the presence of keto groups and as reagents for acetylation under mild conditions . Although they are readily accessible from aldehydes in one step and are relatively reactive, acylals have not been fully utilized as building blocks in organic synthesis.…”