Synthesis 2007(21): 3390-3398  
DOI: 10.1055/s-2007-990818
PAPER
© Georg Thieme Verlag Stuttgart · New York

Microwave-Assisted, Solvent-Free Synthesis of Several Quinazoline Alkaloid Frameworks

Pilar Clederaa, Juan Domingo Sáncheza, Esmeralda Caballeroa, Tamara Yatesb, Elena G. Ramírezc, Carmen Avendañoa, M. Teresa Ramosa, J. Carlos Menéndez*a
a Departamento de Química Orgánica y Farmacéutica, Facultad de Farmacia, Universidad Complutense, 28040 Madrid, Spain
Fax: +34(913)941822; e-Mail: josecm@farm.ucm.es;
b Departamento de Farmacia, Facultad de Farmacia, Universidad de Concepción, Casilla 237, Conceptión, Chile
c Departamento de Farmacia, Facultad de Química, Universidad Nacional Autónoma de México, México D. F. 04510, Mexico
Further Information

Publication History

Received 4 June 2007
Publication Date:
10 October 2007 (online)

Abstract

Microwave irradiation leads to a considerable improvement of the cyclocondensation between anthranilic acid and lactim ethers derived from piperazine-2,5-diones in terms of reaction times, yields, and stereocenter integrity. This reaction has been used to prepare some derivatives of the pyrazino[2,1-b]quinazoline-3,6-dione system present in many quinazoline alkaloids. It could also be applied to the synthesis of compounds containing the complete hexacyclic ring system of the anti-MDR natural product N-acetyl­ardeemin, and other comprising the pentacyclic framework of circumdatin E. The microwave-assisted reaction was also much better than the thermal one when applied to a bis-lactim ether, leading to the corresponding pentacyclic pyrazino[2,1-b:5,4-b′]diquinazoline-8,16-dione in excellent yield.