Atom-economical synthesis of N-heterocycles via cascade inter-/intramolecular C-N bond-forming reactions catalyzed by Ti amides.
Direct and efficient catalytic reactions with excellent regioselectivity for the preparation of a series of substituted isoindoles, isoquinolines, and imidazoles are reported. Reaction of C(6)H(4)(2-CN)C[triple bond]C-R with an array of amines, catalyzed by 10 mol % of [sigma:eta(1):eta(5)-(OCH(2))(Me(2)NCH(2))C(2)B(9)H(9)]Ti(NMe(2)) (1), gives a series of substituted isoindoles in very high yields. In a similar manner, interaction of C(6)H(4)(2-CH(2)CN)C[triple bond]C-Ph with various kinds of amines affords a wide range of substituted isoquinolines. On the other hand, treatment of propargylamines (R'C[triple bond]CCH(2)NHR'') with nitriles in the presence of 10 mol % of 1 produces a class of substituted imidazoles in high yields. A possible reaction mechanism is proposed, involving sequential inter- and intramolecular C-N bond formation via hydroamination/cyclization reaction of cyanoalkynes with amines or nitriles with propargylamines catalyzed by titanium amides.
Shen
Hao
H
Department of Chemistry and Center of Novel Functional Molecules, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China.
Xie
Zuowei
Z
D000577:Amides / Q000737:chemistry*; D002384:Catalysis; D006571:Heterocyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D013237:Stereoisomerism; D014025:Titanium / Q000737:chemistry*
D000577:Amides; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; D014025:Titanium