title: Reaction of acetals with various carbon nucleophiles under non-acidic conditions: C-C bond formation via a pyridinium-type salt.
abstract: Mild substitution reactions of acetals with carbon nucleophiles via the pyridinium-type salts generated by the treatment of acetals with TESOTf-2,4,6-collidine or 2,2'-bipyridyl have been developed. Various carbon nucleophiles, such as organocuprates, silyl enol ethers, enamines, etc., reacted with the pyridinium-type salts to give the corresponding substituted products in good yields. The reactions proceeded under very mild conditions (non-acidic conditions) and thus acid-sensitive functional groups can be tolerated during the reaction. In addition, only an acetal can form the pyridinium-type salt and react with nucleophiles in the presence of a ketal. This unusual selectivity is in contrast to general methods conducted under acidic conditions.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka Suita, Osaka 565-0871, Japan. fujioka@phs.osaka-u.ac.jp
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Fujioka
authors.forename: Kenzo
authors.initials: K
authors.lastname: Yahata
authors.forename: Tomohito
authors.initials: T
authors.lastname: Hamada
authors.forename: Ozora
authors.initials: O
authors.lastname: Kubo
authors.forename: Takashi
authors.initials: T
authors.lastname: Okitsu
authors.forename: Yoshinari
authors.initials: Y
authors.lastname: Sawama
authors.forename: Takuya
authors.initials: T
authors.lastname: Ohnaka
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Maegawa
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Kita
mesh_terms: D000080:Acetals / Q000737:chemistry*; D000143:Acids / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D015394:Molecular Structure; D011725:Pyridines / Q000737:chemistry; D011726:Pyridinium Compounds / Q000737:chemistry*
chemical_list: D000080:Acetals; D000143:Acids; D011725:Pyridines; D011726:Pyridinium Compounds; D002244:Carbon; C007106:gamma-collidine