A Tetranuclear‐Zinc‐Cluster‐Catalyzed Practical and Versatile Deprotection of Acetates and Benzoates

Abstract

A new catalytic deacylation of acetates and benzoates through transesterification with methanol was developed (see scheme). Reactions with various acid- and nucleophile-sensitive functional groups proceeded efficiently in the presence of a catalytic amount of the tetranuclear zinc cluster. The present catalysis is applicable to less-reactive tertiary acetates, the deacylation of which is difficult to achieve by transesterification with other catalysts.

Alkynylation of Aldehydes and Ketones Using the Bu4NOH/H2O/DMSO Catalytic Composition: A Wide‐Scope Methodology

“…1‐Ethynylcyclohexanol (3f): 30 Colorless oil. IR (film): $\tilde {\nu}$ = 3369, 3307, 2935, 2861, 2104, 1463, 1451, 1396, 1350, 1342, 1332, 1318, 1278, 1259, 1181, 1158, 1136, 1070, 1033, 967, 952, 905, 852, 647, 630 cm –1 .…”

Combined Catalytic System of Scandium Triflate and Boronic Ester for Amide Bond Cleavage

“…[8] Herein, we have designed a new cooperative catalyst system by combining two different Lewis acidic atoms. Our findings indicate that the unique combination of a scandium complex and boronic esters works as a catalyst for the alcoholysis of amides.…”

“…[18] Consistently, tris(pentafluorophenyl)borane, which has no oxygen atom bound to boron, had no effects (Table 1, entry 10). We also measured the 1 H NMR spectrum of various combinations of ScA C H T U N G T R E N N U N G (OTf) 3 , boronic ester, and amide in THF-d 8 at 30 8C (Figure 2). By adding ScA C H T U N G T R E N N U N G (OTf) 3 to the solution of amide in THF-d 8 , two peaks corresponding to CONH 2 (* in Figure 2) shifted downfield, indicating that the carbonyl oxygen of amides coordinates to scandium atom (A!C).…”

“…We also measured the 1 H NMR spectrum of various combinations of ScA C H T U N G T R E N N U N G (OTf) 3 , boronic ester, and amide in THF-d 8 at 30 8C (Figure 2). By adding ScA C H T U N G T R E N N U N G (OTf) 3 to the solution of amide in THF-d 8 , two peaks corresponding to CONH 2 (* in Figure 2) shifted downfield, indicating that the carbonyl oxygen of amides coordinates to scandium atom (A!C). Addition of 3d caused no spectral change (A vs. B and C vs. D), suggesting that amide did not coordinate to boron atom.…”

Rh‐Catalyzed Direct Enantioselective Alkynylation of α‐Ketiminoesters

“…[16,17] Such improvement was explained by the fact that the reaction had an induction period; the reaction rate increased after 3 hours at room temperature, indicating the formation of a catalytically active species, most probably, Rh-acetylide complexes, from Rh-acetate precursor 1 f; the intermediacy of such species is supported by the fact that alkyl-substituted terminal alkynes do not undergo reaction at 0 8C. [16] Under the modified reaction conditions, a variety of alkyl-substituted terminal alkynes 3 provided the corre- [a] Determined by 19 F NMR analysis of the crude reaction mixture. (Table 3).…”