Regitz diazo synthesis

Synthesis of 2-diazo-1,3-diketones or 2-diazo-3-oxoesters using sulfonyl azides. 

When only one carbonyl is present, ethylfomiate can be used as an activating auxiliary  

Alternatively, the triazole intermediate may be assembled via a 1,3-dipolar cycloaddition of the enol and mesyl azide  

Name Reactions A Collection of Detailed Mechanisms and Synthetic Applications, DOI 10.1007/978-3-319-03979-4 228, Springer International Publishing Switzerland 2014 

Balasubramanian, M. Regitz diazo synthesis In Name Reactions for Functional Group Transformations, Li, J. J., Ed. Wiley Hoboken, NJ, 2007, pp 658-688. (Review). 

Name Reactions, 4th ed., DOI 10.1007/978-3-642-01053-8 213, Springer-Verlag Berlin Heidelberg 2009 

Synthesis of 2-diazo-l,3-dicarbonyl or 2-diazo-3-ketoesters using sulfonyl azide. 

Regitz, M. Anschutz, W. Bartz, W. Liedhegener, A. Tetrahedron Lett. 1968, 3171. 

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In the laboratory of A. Padwa, a novel synthetic approach to the fully functionalized core of lysergic acid was developed utilizing an intramolecular isomunchone cycloaddition pathway. The key cycloaddition precursor diazo imide was prepared using the standard Regitz diazo tranter conditions. The diazo imide then was heated with catalytic amouts of rhodium(ll)-perfluorobutyrate in dichloromethane to afford the desired cycloadduct as a single diastereomer and in excellent yield. The only reason the authors were not able to complete the total synthesis of lysergic acid was that they could not affect the isomerization of the double bond between the two six-membered rings. 

A versatile stereoselective synthesis of endo,exo-furofuranones was accomplished by R.C.D. Brown and coworkers. One of the key steps was a Rh(ll)-catalyzed C-H insertion reaction and the required diazo lactone was prepared via the Regitz diazo transfer reaction. The 2-acetyl substituted lactone substrate proved to be recalcitrant toward the deacylative diazo transfer under standard conditions. Eventually the authors decided to use the very reactive triflyl azide (TfNs), which was generated in situ under phase-transfer conditions to afford the desired a-diazo lactone. The C-H insertion product was then converted to (+)-methylxanthoxylol. 

Regitz diazo transfer reactions have been reviewed previously.1-3 The following two main routes have been known for the synthesis of diazo compounds (1) diazotization of amines, oximes, nitrosoamines, and hydrazones (2) transfer of the diazo function from tosyl or mesyl azides to active methylene compounds. 

One popular method in the synthesis of a-diazo ketones is in the base-catalyzed diazo group transfer reaction of sulfonyl azides with activated dicarbonyl compounds The Regitz Diazo Reaction) While direct diazo transfer to ketone enolates is usually not feasible, a two step deformylative diazo transfer strategy has been employed, whereby a ketone is first... 

Regitz, M. Maas, G. Aliphatic Diazo Compounds — Properties and Synthesis Academic Press, New York, in press... 

M. Regitz and G. Maas, Diazo Compounds—Properties and Synthesis, Academic Press, Orlando, FL,... 

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