2-Diazo-3- propionates

CYCLOPROPANES Methyl diazo propionate. Copper(l)oxide-(-Butyl isonitrile. CYCLOPROPENONE Tri-fi-butyltin hydride. 

Shi G, Xu Y (1989) Ethyl 3-trifluoro-2-diazo-propionate as a potentially useful CFj-containing building block preparation and [Rh(OAc)2]2-catalysed reaction with nitriles. J Chem Soc Chem Commun 1989 607-608... 

To set the stage for the crucial aza-Robinson annulation, a reaction in which the nucleophilic character of the newly introduced thiolactam function is expected to play an important role, it is necessary to manipulate the methyl propionate side chain in 19. To this end, alkaline hydrolysis of the methyl ester in 19, followed by treatment of the resulting carboxylic acid with isobutyl chlorofor-mate, provides a mixed anhydride. The latter substance is a reactive acylating agent that combines smoothly with diazomethane to give diazo ketone 12 (77 % overall yield from 19). 

The majority of pyrimido[4,5-c]pyridazines have been prepared from pyrimidine precursors. The chloropyrimidines (176) give the desired heterocyclic ring (177) on reaction with hydrazine (72BSF1483). Hydrazine also reacts with ethyl a-diazo-/3-oxo-5-(4-chloro-2-methylthiopyrimidine)propionate (178) to give the pyrimido[4,5-c]pyridazine-3-carboxamide (78). A mechanism for this interesting reaction has been proposed as shown, on the basis of the detection of hydrogen azide in the reaction mixture. There is no precedent for the reaction of the a-carbon of a-diazo-/3-oxopropionates with nucleophiles under basic conditions (76CPB2637). 

Taylor, E.C., and Davies, H.M.L., Rhodium(II) acetate-catalyzed reaction of ethyl 2-diazo-3-oxopent-4-enoates. Simple routes to 4-aryl-2-hydroxy-l-naphthoates and P,y-iinsaliiralcd esters. The dianion of ethyl 4-(diethylphosphono)acetoacetate as a propionate homoenolate equivalent, Tetrahedron Lett., 24, 5453. 1983. 

Polymer-bound arylsulfonyl azides have been tested as diazo transfer reagents (Roush et al., 1974 Diirr et al., 1981). Yields with diethyl malonate and acetylace-tone are slightly lower than those with 4-toluenesulfonyl azide. In contrast to these compounds with two neighboring activating groups, yields with monoactivated methylenes (ethyl propionate and cyclohexanone) are much lower. This method is therefore, not recommended in the described form. 

As shown by the preceeding example, alkenes with an electron donor substituent on one of the alkene C-atoms form dihydrotriazoles with that substituent in the 5-position. Many additional examples, particularly with enamines, can be found in the literature (e.g., Dalla Croce and Stradi, 1977). Alkenes with an electron-acceptor substituent generally add azides in the opposite manner, i. e., the substituent will be in the 4-position. Examples of such cycloadditions have been described by Huisgen et al. (1966 b). These authors synthesized alkyl 2-diazo-3-(phenylamino)propionates... 

Formic acid Propionic acid D-a-hydro wisovaleric acid ot-n-hexyl-p,y-dihydroxypentanoic acid 6-diazo-5-oxohexanoic acid 6-methylheptanoic acid (+)-6-methyloctanoic acid 3-hydroxydecanoic acid /3-hydroxytridecanoic acid (+)-12-methyltetradecanoic acid... 

---