Chikao Hashimoto

Esterification of alkene with cerium(IV) sulfate in carboxylic acid

Reaction of alkenes [cyclohexene (1), cycloheptene (2), cyclooctene (3), 1-heptene (4), 1-octene (5), styrene (6), 1,7-octadiene (7), indene (8), and 1,2-dihydronaphthalene (9)] with cerium(IV) sulfate (CS) in carboxylic acids [formic acid, acetic acid, and propionic acid] readily yielded the corresponding carboxylic esters. This addition reaction follows the Markovnikov rule. This reaction provides a new simple method for preparing carboxylic esters from alkenes. It was also found that this method is useful for formylation.

An efficient method for the synthesis of phenacyl ester-protected dipeptides using neutral alumina-supported sodium carbonate ‘Na2CO3/n-Al2O3’

In the synthesis of dipeptides (Boc‐AA1‐AA2‐OPac: AA1 and AA2 represent amino acids) protected by phenacyl (Pac) ester, amines and solid bases as the base for the conversion of the trifluoroacetic acid (TFA) salt of the amino component (TFA·H‐AA2‐OPac) into the corresponding free amino component (H‐AA2‐OPac) were examined. The synthesis of a dipeptide (Boc‐Ala‐Gly‐OPac) using amines for the conversion afforded an unsatisfactory yield with by‐products. On the other hand, the use of neutral alumina‐supported Na2CO3 (Na2CO3/n‐Al2O3) as a solid base for the conversion provided the dipeptide in a quantitative yield without by‐products. The application of Na2CO3/n‐Al2O3 to the synthesis of some dipeptides protected by Pac ester gave the desired peptides in excellent yields. Copyright