title: A convenient synthesis of 1,1-disubstituted 1,2,3,4-tetrahydroisoquinolines via Pictet-Spengler reaction using titanium(IV) isopropoxide and acetic-formic anhydride.
abstract: A synthesis of 1,1-disubstituted 1,2,3,4-tetrahydroisoquinolines (6) was achieved in a highly efficient manner via Pictet-Spengler reaction of arylethylamines (1) and acyclic and cyclic ketones (2) using titanium (IV) isopropoxide and acetic-formic anhydride. The cyclization of the in situ formed acyliminium ion (4) to N-formyl 1,2,3,4-tetrahydroisoquinoline (5) was greatly facilitated by using trifluoroacetic acid as an additional reagent. The Pictet-Spengler reaction was carried out by one pot procedure, providing a convenient and effective method for preparing various 1,2,3,4-tetrahydroisoquinolines.
authors.affiliation: Showa Pharmaceutical University, Machida, Tokyo, Japan. horiguti@ac.shoyaku.ac.jp
authors.forename: Yoshie
authors.initials: Y
authors.lastname: Horiguchi
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Kodama
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Nakamura
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Yoshimura
authors.forename: Kaori
authors.initials: K
authors.lastname: Hanezi
authors.forename: Hiroko
authors.initials: H
authors.lastname: Hamada
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Saitoh
authors.forename: Takehiro
authors.initials: T
authors.lastname: Sano
mesh_terms: D000812:Anhydrides; D007546:Isoquinolines / Q000138:chemical synthesis*; D009942:Organometallic Compounds; D014025:Titanium
chemical_list: D000812:Anhydrides; D007546:Isoquinolines; D009942:Organometallic Compounds; C102815:titanium isopropoxide; D014025:Titanium