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Synlett 2010(8): 1260-1264  
DOI: 10.1055/s-0029-1219801
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Recyclable Iron/Graphite Catalyst for C-S Cross Coupling of Thiols with Aryl Halides under Ligand-Free Conditions

Vijay Kumar Akkilagunta, Vutukuri Prakash Reddy, Kakulapati Rama Rao*
Organic Chemistry Division-I, Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad 500607, India
Fax: +91(40)27160512; e-Mail: kakulapatirama@gmail.com;
Further Information

Publication History

Received 22 January 2010
Publication Date:
25 March 2010 (online)

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Abstract

A recyclable iron/graphite (Fe/Cg) catalyst for the efficient C-S cross-coupling of various iodoarenes with aromatic/­aliphatic thiols has been developed under ligand-free conditions (26 examples, up to 99% yield). The catalyst can be easily recovered and recycled up to seven cycles without loss of activity.

Key words

arylhalides - cross-coupling - recyclable catalyst - iron - thiols

12

Procedure for the catalyst preparation, characterization can be adopted from the experimental section in the Supporting Information.

13

Percentage weight with respect to iron (not mol%).

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Experimental section for the spectral discussion.

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Typical Procedure for C-S Cross-Coupling Fe/Cg (7 wt%, 162 mg) was added to a 25 mL flask, which was previously charged with iodoarene (1.2 mmol), thiol
(1 mmol) and KOH (2.0 equiv). Dry DMSO (1.5 mL) was added while purging the flask with nitrogen. The round-bottom flask was purged once again and back filled with nitrogen and heated in an oil bath at 125 ˚C for a period of 24 h after which the flask was removed from the oil bath and allowed to come to r.t. Fe/Cg was removed by ultracentri-fugation at 8000 rpm. After which the reaction mixture was poured into H2O (5 mL), and the aqueous layer was extracted with EtOAc (3 × 10 mL).