Synthesis 2007(16): 2503-2512  
DOI: 10.1055/s-2007-983790
PAPER
© Georg Thieme Verlag Stuttgart · New York

A Rapid Intramolecular Imino Diels-Alder Reaction of Aminoanthraquinones with Citronellal or Prenylated Salicylaldehydes: Substituent Effect on Changing the Reaction Pathway from Diels-Alder to Ene-Type Cyclization

Vikram Gaddam, Ramu Meesala, Rajagopal Nagarajan*
School of Chemistry, University of Hyderabad, Central University (P.O.), Hyderabad 500046, India
Fax: +91(40)23012460; e-Mail: rnsc@uohyd.ernet.in;
Further Information

Publication History

Received 10 April 2007
Publication Date:
12 July 2007 (online)

Abstract

The reaction of 1-aminoanthraquinone with citronellal or substituted prenylated salicylaldehyde catalyzed by triphenylphosphonium perchlorate (TPPP) is reported. The nature of the substituents in salicylaldehyde changes the reaction pathway from Diels-Alder to ene-type cyclization.

13

The CCDC deposition number for the compound 2 is 611480; unit cell parameters: a = 14.5594(14), b = 8.4736(8), c = 15.8853(16), β = 104.635(2); space group
P2(1)/c.

14

The CCDC deposition number for compound 5 is 611481; unit cell parameters: a = 16.8420(15), b = 11.2255(10), c = 10.4503(9), space group Pca21.

16

The CCDC deposition number for compound 8 is 611482; unit cell parameters: a = 7.1683(8), b = 11.0149(12), c = 12.9380(14), α = 92.427(2), β = 104. 027(2), γ = 98.775(2), space group P-1.

17

The CCDC deposition number for compound 9c is 611484; unit cell parameters: a = 13.2240(17), b = 13.4610(17), c = 12.9530(17), β = 115.528(2), space group P2(1)/c.

18

The CCDC deposition number for compound 10a is 611483; unit cell parameters: a = 7.2367(11), b = 27.623(4), c = 12.2850(18), β = 102.816(3), space group P2(1)/n.