Ethyl diazoacetate Lewis acid catalyzed

Reaction of 7V-benzylidine-o-anisidine with ethyl diazoacetate as the carbene-donor fragment in the presence of SnCU as the catalyst (5 mol %) gives the cw-aziridine selectively as the catalyst in reasonable yields (Eq. 65) [98], In the presence of SnCU no reaction occurs. This imine-SnC intermediate gives important information about the reaction course for the Lewis acid-catalyzed aziridination of imines. 

In a mechanistic study on the Lewis acid catalyzed addition of ethyl diazoacetate to ketones a similar profile of rearrangement to the 3-keto esters was observed (Scheme 9). In the same reaction with acetophenones, substitution on the benzene ring was found to only slightly affect the otherwise 90 10 preference for migration of aryl versus methyl. ... 

The Lewis acid catalyzed expansion with ethyl diazoacetate also gives good regioselectivity, with a preference for migration of the non-ring-fusion cartran (equations 11-16). The use of SbCls as die Lewis acid at -78 C was reported to improve the regioselectivity in one case (equation 14). ... 

Aldehydes are efficiently converted to /3-diketo esters in 50-90 % yield by addition of ethyl diazoacetate in the presence of SnCl2 (Eq. 5). Although the reaction can be effected by a variety of Lewis acids, SnCl2, BF3, and GeCl2 are the most effective [14]. 1,3-Diketones can be prepared in 42-90 % yield by SnCl2-catalyzed reaction of a-diazo ketones with aldehydes (Eq. 6) [15]. 

Several substituted benzo[ ]furans were synthesized efficiently in one-pot procedures by reaction of salicyaldehydes and ethyl diazoacetate in the presence of HBF/EtjO in high yields as shown below. A plausible mechanism was also given <0681711>. Two types of naphtha[2,3-fc]furan derivatives were made respectively by Lewis acid and HCl catalyzed ring cyclizations <06T8045>. AuBrj-catalyzed [4+2] benzannulation between enynal units and enol ethers was also applied to prepare benzo[Z)]furans <06JOC5249>. 

A screen of chiral Lewis acids was carried out by Jorgensen, but this effort failed to reveal any effective enantioselective catalysts [31]. However, very recently Wulff disclosed an extremely exciting result in the VAPOL-BH3 catalyzed reaction between ethyl diazoacetate and imines (Scheme 14) [32]. Although the details had not been published at the time this chapter was written, it seems likely that this method will constitute an important breakthrough and establish a new direction for future research in the field of asymmetric aziridination catalysis. 

Insertions into Aldehyde C-H Bonds. The a-diazo ketones (and esters) derived from diazomethane and an acid chloride (or chloroformate) will also insert into the C-H bond of aldehydes to give 1,3-dicarbonyl derivatives. The reaction is catalyzed by SnCL, but some simple Lewis acids, such as BF3 etherate, also work. The reaction works well for ahphatic aldehydes, but gives variable results with aromatic aldehydes, at times giving none of the desired diketone (eq 32). StericaUy hindered aldehydes will also participate in this reaction, as illustratedin eq 33 with the reaction of ethyl a-diazoacetate and pivaldehyde. In a related reaction, a-diazo phosphonates and sulfonates will react with aldehydes in the presence of SnCL to give the corresponding -keto phosphonates and sulfonates. This reaction is a practical alternative to the Arbuzov reaction for the synthesis of these species. 

In 1998, Hossain et al. reported the catalytic synthesis of aziridines, using an achiral iron Lewis acid-THF adduct, [CpFe(CO)2(THF)]+[BF4] (108). The reaction was generally ds-aziridine selective. With this approach, cis selectivity is now known to be typical, since most catalytic reactions mainly yield ds-aziridine. In 2001, they continuously reported the reason for the apparent cis-aziridine selectivity in the reaction of ethyl diazoacetate (10) with JV-benzylidene aniline (109a), catalyzed by (108) [36]. The catalytic reaction produces both cis- and trans-aziridines. Once... 

The iron Lewis acid complex, [CpFe(CO)2(THF)][BF4], has been shown to catalyze the reaction of ethyl diazoacetate and phenyldiazomethane with olefins to form cyclopropanes. The selectivity of the reaction suggests the involvement of an intermediate iron carbene [Gp(C0)2Fe =GH(G02Et) ]. ... 

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