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Synthesis 2008(5): 661-689  
DOI: 10.1055/s-2008-1032179
REVIEW
© Georg Thieme Verlag Stuttgart · New York

Mechanism and Application of the Newman-Kwart O→S Rearrangement of O-Aryl Thiocarbamates

Guy C. Lloyd-Jones*a, Jonathan D. Moseleyb, Joseph S. Rennya
a School of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, UK
Fax: +44(117)9298611; e-Mail: guy.lloyd-jones@bris.ac.uk;
b AstraZeneca, Avlon Works, Severn Road, Hallen, Bristol BS10 7ZE, UK
Fax: +44(117)9385081;
Further Information

Publication History

Received 1 November 2007
Publication Date:
18 February 2008 (online)

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Abstract

This literature review focuses on the thermal rearrangement of O-aryl thiocarbamates to yield the corresponding S-aryl thiocarbamates: the Newman-Kwart rearrangement. The purpose of the review is to highlight the utility of the rearrangement which provides a key step in an efficient route to convert phenols into thiophenols. The scope of the Newman-Kwart rearrangement is illustrated by way of numerous examples of its application to the preparation of Ar-S species ranging from large-scale industrial processes through to the synthesis of complex organic molecules such as ligands and supramolecular structures. The review contains 238 references and covers just over 40 years of the literature, from the first reports of the rearrangement by Edwards and Pianka in 1965 up to mid-2007.

1 Introduction

2 The Newman-Kwart Rearrangement (NKR)

2.1 Background and History

2.2 Preparation of O-Aryl Thiocarbamates for NKR and Subsequent­ Cleavage

2.3 Mechanism of Rearrangement

2.4 Nonclassical Conditions for Rearrangement

2.5 Allylic and Benzylic Rearrangements

2.6 Competing Pathways

3 Applications

3.1 General Routes to Ar-SH

3.2 Medicinal Chemistry

3.3 Scale-Up of the NKR and Process Development

3.4 Agrochemicals and Dyestuffs

3.5 Ligand Synthesis

3.6 Supramolecular Synthesis

3.7 Miscellaneous Applications: Odour Reduction, Molecular Switches, Polymers and Dendrimers, Organocatalysts and Helicenes

4 Summary and Outlook

Key words

Newman-Kwart - aryl thiocarbamates - aryl thiols - thermal rearrangement - mechanism