Synlett 2004(12): 2163-2164  
DOI: 10.1055/s-2004-831292
LETTER
© Georg Thieme Verlag Stuttgart · New York

Synthesis of Benzocyclobutanes through Ring Transformation Reactions of 2H-pyran-2-ones [1]

Diptesh Sila, Ashoke Sharonb, Ramendra Pratapa, Prakas R. Maulikb, Vishnu Ji Ram*a
a Medicinal Chemistry Division, Central Drug Research Institute, Lucknow-226001, India
Fax: +91(522)2223405; e-Mail: vjiram@yahoo.com;
b Molecular & Structural Biology Division, Central Drug Research Institute, Lucknow-226001, India
Further Information

Publication History

Received 1 June 2004
Publication Date:
06 August 2004 (online)

Abstract

A one-pot synthesis of benzocyclobutane (3a-n) has been developed through base-induced ring transformation reactions of 6-aryl-4-substituted-2H-pyran-2-one-3-carbonitriles (1a-c) and methyl 6-aryl-4-methylsulfanyl-2H-pyran-2-one-3-carboxylate (1d) by cyclobutanone.

1

CDRI Communication No: 6532.

1

CDRI Communication No: 6532.

29

Typical Procedure of 3: A mixture of 2H-pyran-2-one 1
(1 mmol), cyclobutanone (1 mmol) and powdered KOH (1.5 mmol) in dry DMF was stirred for 24 h at r.t. The reaction mixture was poured onto ice-water with vigorous stirring and finally neutralized with 10% HCl. The separated solid was filtered, washed with H2O and dried. The crude product was purified by silica gel column chromatography. Compound 3c: mp 144-145 °C. Yield: 61%. IR (KBr): 2215 cm-1. 1H NMR (200 MHz, CDCl3): δ = 2.58 (s, 3 H, SCH3), 3.29-3.31 (m, 4 H, CH2), 4.07 (s, 5 H, ArH), 4.42-4.44 (m, 2 H, ArH), 4.66-4.68 (m, 2 H, ArH), 7.27 (s, 1 H, ArH). FAB (MS): 360 [M+ + 1]. Further details of the crystal structure investigation of 3c can be obtained from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge, CB2 1EZ, UK (CCDC deposition No. of 3c: 235153).