Olefins cyclopropanations, dimethyl diazomalonate

Homogeneous and heterogeneous catalysis of bismethoxycarbonylcarbene addition to olefins and the copper- and silver-catalysed decompositions of dimethyl diazomalonate all result in stereospecific cyclopropanation, although three-membered ring formation is accompained by significant amounts of allyic C—H insertions pro-... 

A general examination of the addition of bis(methoxycarbonyl)carbene, generated under homogeneous and heterogeneous conditions by the copper- or silver-catalysed decomposition of dimethyl diazomalonate, to olefins has been made. Cyclohexene was found to react five times faster than 1-methylcyclohexene using an iodo(trimethyl phosphite)copper(i) catalyst to give the cyclopropane derivative. 

Cyclopropanation ([2 +1] Cycloaddition). Cu - and Rh -catalyzed cyclopropanation of olefins with dimethyldiazo malonate was used efficiently for the preparation of cyclopropane dicarboxylates. Methylenecyclopropanes were employed in this reaction to afford bicyclopentane derivatives in moderate yields and high diastereoselectivity (eq 17). Utilization of dimethyl diazomalonate in enantioselective cyclopropanation is a very challenging task. Thus the highest ee s obtained in the presence of Rh2(45-MEAZ)4 did not exceed 50% (eq 18). Cyclopropanation of olefins was also performed in the presence of catalytic amounts of copper(II) and osmium(II). ... 

Cyclopropanation of aromatic and heteroaromatic compounds with dimethyl diazomalonate in the presence of Rh2(OAc)4 is usually accompanied by dissociation of one of the cyclopropane bonds. In reaction of )V-protected indoles this led to a very efficient introduction of the malonate substituent at position 3 (eq 21). When the 3-position was substituted, the malonate moiety was installed into the 2-position, however, yields were significantly diminished. Remarkably, no cyclopropanation of the a-olefin at the side chain was observed (eq 22) Although the reactions featured here represent a formal insertion of the carbenoid species... 

Ando et aU have published details of the thermal reaction of diazo-com-pounds with sulphides. For the reaction to be of use, a stabilized diazo-compound and a dialkyl sulphide must be employed, but some aryl sulphides have been used successfully. Thus, diazomalonate and dimethyl sulphide afforded the ylide in 75% yield, and the use of diphenyl sulphide afforded ylide in 85% yield. The use of olefinic sulphides afforded two competitive sites for attack by the carbene presumably formed from the diazo-compound. Diazoacetate and the vinyl sulphide (2) produced a 5% yield of the cyclopropane, resulting from carbene attack at the double bond, and a 39% yield of a rearranged vinyl sulphide (3), resulting from carbene... 

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