Synlett 2005(7): 1185-1187  
DOI: 10.1055/s-2005-865230
LETTER
© Georg Thieme Verlag Stuttgart · New York

A Direct Preparation of Functionalized Aryl and Heteroaryl Disulfides from Functionalized Zinc Organometallics by Using Sulfur Monochloride (S2Cl2)

Tobias J. Korn, Paul Knochel*
Department Chemie, Ludwig-Maximilians-Universität, Butenandtstrasse 5-13, 81377 München, Germany
Fax: +49(89)218077680; e-Mail: Paul.Knochel@cup.uni-muenchen.de;
Further Information

Publication History

Received 1 March 2005
Publication Date:
14 April 2005 (online)

Abstract

A range of functionalized aryl and heteroaryl disulfides has been prepared from zinc organometallics by using sulfur monochloride (S2Cl2). The zinc reagents were obtained by transmetalation from magnesium or lithium reagents with ZnBr2.

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Typical Procedure. Preparation of the Functionalized Indolyl Disulfide 2k.
A dry and nitrogen flushed 25 mL Schlenk flask, equipped with a rubber septum and a magnetic stirring bar, was charged with dry THF (5.0 mL) and 3-iodo-1-(phenyl-methyl)-1H-indole-2-carboxylic acid ethyl ester (403 mg, 0.99 mmol). The solution was cooled to -20 °C and
i-PrMgCl (1.12 mL, 1.00 mmol, 0.9 M in THF) was added slowly. The reaction mixture was stirred at that temperature until the I/Mg-exchange was complete (0.5 h, checked by GC), cooled to -40 °C, ZnBr2 (0.64 mL, 1.09 mmol, 1.7 M in THF) was added and the white suspension was stirred for 30 min at that temperature. The heterogeneous mixture was cooled to -80 °C and S2Cl2 (67 mg, 0.50 mmol) was added dropwise. After 10 min the reaction mixture was quenched with sat. NH4Cl solution (50 mL), extracted with Et2O (3 × 50 mL), the combined organic layers were washed with brine (50 mL), dried over MgSO4 and concentrated in vacuo. Flash chromatographic purification on silica gel (pentane-Et2O = 3:1) furnished 2k as a light yellow solid (193 mg, 0.31 mmol, 62%, mp >240 °C decomposition).