APPLIED ORGANOMETALLIC CHEMISTRY Appl. Organometal. Chem. 2004; 18: 398–400 Main Group Metal Compounds Published online in Wiley InterScience (www.interscience.wiley.com). DOI:10.1002/aoc.681 Studies on the catalysis of the reaction of organotin phenoxides with bis(2,2,2-trichloroethyl) azodicarboxylate by lithium perchlorate Wojciech J. Kinart 1 *, Cezary M. Kinart 2 , Quang T. Tran 1 , Rafal Oszcz ¸ eda 1 and Ryszard B. Nazarski 1 1 Department of Organic Chemistry, University of Lodz, Narutowicza 68, 90-136 Lodz, Poland. 2 Department of Chemistry, University of Lodz, Pomorska 163, 90-236 Lodz, Poland Received 26 March 2004; Revised 9 April 2004; Accepted 27 April 2004 Organotin phenoxides, which are distinctly more active than the corresponding phenols, react at room temperature with bis(2,2,2-trichloroethyl) azodicarboxylate to produce para-substituted phenolic hydrazides in high yields. Copyright  2004 John Wiley & Sons, Ltd. KEYWORDS: organotin phenoxides; bis(2,2,2-trichloroethyl) azodicarboxylate; lithium perchlorate; phenolic hydrazides INTRODUCTION Diprotected monosubstituted hydrazine derivatives are ver- satile intermediates in the synthesis of aromatic amines, 1 aryl hydrazines, 2,3 substituted hydrazine derivatives, 4–6 azatides (as important peptidomimetics), 7–9 and β -strand mimics. 10 These products are used in the preparation of a wide variety of biologically and industrially valuable compounds. 4–6,11,12 Monosubstituted hydrazines are also intermediates in the preparation of heterocyclic compounds such as pyrazoles, 13 indazoles, 14 imidazolinones, 15 and cinnolines. 16 Moreover, 2-heteroaryl hydrazines 17 are interesting synthetic targets due to their efficiency as ligands for a variety of metal complexes. 18 – 20 Diprotected aryl hydrazines are generally prepared by electrophilic amination 1,14,21 – 26 of electron-rich arens utilizing dialkyl azodicarboxylates or via the reaction of tert-butyl carbazates with boronic acids catalysed by cuprous chloride at room temperature. 27 Previously, 26 we have shown that organotin phenoxides react with diethyl azodicarboxy- late (DEAD) in diethyl ether in the presence of lithium perchlorate (LiClO 4 ) to give the corresponding ring-aminated phenols. Phenols do not react with DEAD under these conditions. Leblanc and co-workers 1 have shown that the reactions of electron-rich arens with bis(2,2,2-trichloroethyl) azodicarboxylate in diethyl ether and acetone are strongly catalysed by lithium perchlorate (3 M solutions of LiClO 4 in Et 2 O and acetone). A number of reactions have recently *Correspondence to: Wojciech J. Kinart, Department of Organic Chemistry, University of Lodz, Narutowicza 68, 90-136 Lodz, Poland. E-mail: ckinart@uni.lodz.pl been shown to be surprisingly susceptible to such cataly- sis (typically, 5 M solutions in diethyl ether). 28 – 34 Davies 35 has proved that O-metallation of alcohols and enols raises their reactivity towards electrophiles such as aldehydes and alkyl or acyl halides. Therefore, we assumed that the polarity of the M δ+ –O δ− –Ar bond would be expected to promote the reaction with enophiles such as bis(2,2,2-trichloroethyl) azodicarboxylate. We have decided to use organotin phe- noxides (n-Bu 3 SnOAr) because of the pronounced polarity of the Sn– O bond and simplicity of their preparation. Although bis(2,2,2-trichloroethyl) azodicarboxylate is more expensive and less stable than DEAD, it is also more reactive in reac- tions with electron-rich arens. Therefore, we assume that its application may sometimes be an alternative to DEAD. RESULTS AND DISCUSSION We have studied the reactions of different phenols 1a – d and corresponding tin phenoxides 2a – d with bis(2,2,2- trichloroethyl) azodicarboxylate carried out in 5 M solution of LiClO 4 in diethyl ether (Fig. 1). Previous studies with this azo enophile were carried out at elevated temperatures. 1 However, it is known that heating of solution of LiClO 4 in Et 2 O or acetone may be hazardous. We hoped that the use of more concentrated solutions of LiClO 4 would enable us to carry out reactions with bis(2,2,2-trichloroethyl) azodicarboxylate at room temperature. The addition products 4a – b obtained by us were isolated by chromatography on silica. The yields of this reaction for different phenolic Copyright  2004 John Wiley & Sons, Ltd.