Deformylation diazo group transfer reaction

Diazojasmonate (64) is prepared from the 5-formyl derivative of 63 via a deformylation diazo group transfer reaction with the 4-carboxybenzenesulphonyl derivative.23... 

The importance of a-diazo ketones as synthetic intermediates has led to the development of a number of general methods for their preparation.5 Particularly popular approaches include the acylation of diazo alkanes and the base-catalyzed "diazo group transfer" reaction of sulfonyl azides with 8-dicarbonyl compounds.6-7 While direct diazo transfer to ketone enolates is usually not a feasible process,8-9 diazo transfer to simple ketones can be achieved in two steps by employing an indirect deformylative diazo transfer strategy in which the ketone is first formylated under Claisen condensation conditions, and then treated with a sulfonyl azide reagent such as p-toluenesulfonyl azide.6a,6c,9,i0,11... 

Regitz, M., Rueter, J. Reactions of CH-active compounds with azides. XVIII. Synthesis of 2-oxo-1-diazo cycloalkanes by deformylative diazo-group transfer. Chem. Ber. 1968, 101, 1263-1270. 

Regitz, M., Menz, F., Lledhegener, A. Reactions of CH-actIve compounds with azides. XXVIII. Synthesis of a, 3-unsaturated dIazoketones by deformylating diazo group transfer. Liebigs Ann. Chem. 1970, 739, 174-184. 

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... 

In addition to previously described syntheses4-5 by diazo group transfer with deformylation,6 2-diazocyclohexanone has been prepared by two variants of this method. In one, the reaction of 2-(hydroxymethylene)cyclohexanone with -toluene-sulfonyl azide is carried out in ether/diethylamine, and an enamine is assumed to be formed as an intermediate 7 in the other, the sodium salt of the hydroxymethylene compound was treated with the lithium salt of p-carboxybenzenesulfonyl azide... 

The reaction sequence is called the Regitz diazo transfer and requires active methylene compounds as substrates/ Hence it is common to use formic esters to create P-carbonyl compounds from ketones or aldehydes in an aldol reaction. These are used as substrates for deformy-lative diazo transfer reactions in which the diazo group is transferred and the formyl group is removed in one concerted step. The mechanism of the deformylative diazo transfer is shown below. In this case the bulky base NaHMDS ensures deprotonation at the less-hindered a-position of 3, forming the so-called kinetic enolate 13. This enolate is formylated by ethyl formate yielding the P-formyl ketone 14, which is used as substrate in the deformylative diazo transfer. 

The 3-acetyl group on an indole can be transformed into an a-diazoketone by a deformylative diazo transfer process, involving treatment with base and trifluoroacetylation followed by base-catalyzed reaction with mesylazide (Scheme 136) <90JOC1959>. This methodology has been used in a synthesis of the oxazolyl indole alkaloid pimprinine <9481021 >. 

---