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A divergent synthesis of α-substituted bromomethyl γ-lactones was developed, which involves the diastereoselective bromolactonization of α-substituted 4-pentenoic acids and 4-pentenamides via umpolung of bromide by use of alkali metal bromide and Oxone (potassium peroxymonosulfate mixture, 2KHSO5·KHSO4·K2SO4) to obtain mainly cis-products from α-substituted 4-pentenoic acids and trans-products from α-substituted 4-pentenamides, and it was found that the bromonium species generated from KBr and Oxone had higher activity than N-bromosuccinimide. Furthermore, the asymmetric total synthesis of (+)-dubiusamine C, which was isolated as a minor diastereomer from Pandanus dubius, was accomplished for the first time through the cis-selective bromolactonization of (S)-α-methyl-4-pentenoic acid in nine linear steps and 36% overall yield. [ABSTRACT FROM AUTHOR]

A bromide-catalyzed oxidation of alcohols was developed which proceeded in the presence of an alkali metal bromide and an oxidant under mild conditions. The reaction involved an organic-molecule-free oxidation using KBr and Oxone and a Brønsted acid assisted oxidation using KBr and aqueous H2O2 solution to provide a broad range of carbonyl compounds in high yields. Moreover, the bromide-catalyzed oxidation of primary alcohols enabled the divergent synthesis of carboxylic acids and aldehydes under both reaction conditions in the presence of TEMPO. A possible catalytic mechanism was suggested on the basis of various mechanistic studies. [ABSTRACT FROM AUTHOR]

Various benzylic alcohols and aliphatic secondary alcohols were smoothly oxidized to the corresponding aromatic aldehydes, aromatic ketones, and aliphatic ketones, respectively, with the novel 1-acetoxy-5-nitro-1,2-benziodoxole-3(1H)-one (ANBX) alone, a trivalent iodine prepared from the oxidation of 2-iodo-5- nitrobenzoic acid with MCPBA. The present reaction is the first effective method for the oxidation of alcohols with a trivalent iodine alone under mild reaction conditions. [ABSTRACT FROM AUTHOR]

The intramolecular α-alkylation of β-alkoxy-α-amino esters derived from l-serine proceeded predominantly over β-elimination. When β-alkoxy-α-amino esters were treated with powdered CsOH in DMSO at 20 °C, α-alkoxymethyl cyclic amino esters were obtained in up to 94% ee. Optically active THF amino acids were synthesized for the first time by the present method. [ABSTRACT FROM AUTHOR]

A variety of ethylarenes were converted into the corresponding primary aromatic amides in good yields via treatment with N-bromosuccinimide in the presence of a catalytic amount of 2,2'-azobis(isobutyronitrile) in a mixture of ethyl acetate and water, acetonitrile and water, or chloroform and water, followed by reaction with molecular iodine and aq NH3 in one pot. It was found that aryl α-bromomethyl ketones and/or aryl methyl ketones were formed at the first reaction step and their iodoform-type reaction occurred at the second reaction step to provide primary aromatic amides. The present reaction is a useful and practical transition-metal-free method for the preparation of primary aromatic amides from ethylarenes. [ABSTRACT FROM AUTHOR]

A variety of ethylarenes were converted into the corresponding primary aromatic amides in good yields via treatment with N-bromosuccinimide in the presence of a catalytic amount of 2,2'-azobis(isobutyronitrile) in a mixture of ethyl acetate and water, acetonitrile and water, or chloroform and water, followed by reaction with molecular iodine and aq NH3 in one pot. It was found that aryl α-bromomethyl ketones and/or aryl methyl ketones were formed at the first reaction step and their iodoform-type reaction occurred at the second reaction step to provide primary aromatic amides. The present reaction is a useful and practical transition-metal-free method for the preparation of primary aromatic amides from ethylarenes. [ABSTRACT FROM AUTHOR]