Amino-esters, diazoesters with

Diazoesters react with amines with a rhodium catalyst to give a-amino esters.Diazoesters also react with aldehydes and a rhodium catalyst, and the product is an a,()-epoxy ester.Diazoalkanes react similarly with aldehydes to give an alkene (Me3SiCH=N2 + ArCHO ArCH=CHOSiMe3). ... 

In conjunction with their Friedel-Crafts alkylation, Terada et al. found phosphoric acid (R)-3m (2 mol%, R = 9-anthryl) bearing a bulky 9-anthryl group to mediate the asymmetric Friedel-Crafts-type reaction of a-diazoester 22a with iV-acylated aldimines 26 (Scheme 10). a-Diazo-P-amino esters 27 were obtained in moderate yields (62-89%) and very good enantioselectivities (91-97% ee) [20],... 

Kobayashi et al. found that lanthanide triflates were excellent catalysts for activation of C-N double bonds —activation by other Lewis acids required more than stoichiometric amounts of the acids. Examples were aza Diels-Alder reactions, the Man-nich-type reaction of A-(a-aminoalkyl)benzotriazoles with silyl enol ethers, the 1,3-dipolar cycloaddition of nitrones to alkenes, the 1,2-cycloaddition of diazoesters to imines, and the nucleophilic addition reactions to imines [24], These reactions are efficiently catalyzed by Yb(OTf)3. The arylimines reacted with Danishefsky s diene to give the dihydropyridones (Eq. 14) [25,26], The arylimines acted as the azadienes when reacted with cyclopentadiene, vinyl ethers or vinyl thioethers, providing the tet-rahydroquinolines (Eq. 15). Silyl enol ethers derived from esters, ketones, and thio-esters reacted with N-(a-aminoalkyl)benzotriazoles to give the /5-amino carbonyl compounds (Eq. 16) [27]. The diastereoselectivity was independent of the geometry of the silyl enol ethers, and favored the anti products. Nitrones, prepared in situ from aldehydes and N-substituted hydroxylamines, added to alkenes to afford isoxazoli-dines (Eq. 17) [28]. Addition of diazoesters to imines afforded CK-aziridines as the major products (Eq. 18) [29]. In all the reactions the imines could be generated in situ and the three-component coupling reactions proceeded smoothly in one pot. 

Isocyanoacrylic acid esters are useful as precursors of heterocyclic and unsaturated amino-acids. These compounds are prepared in a stereoselective manner and in good yield using the Wittig-Horner reaction of t-butyl(diphenylphosphinyl)isocyanoacetate with aldehydes. cw-Enoates have been prepared by the reaction of a-diazoesters with Rh(OAc)2. An interesting one-pot synthesis of a-fluoro-a,/3-unsaturated esters from ethyl chloromalonate and carbonyl compounds works well using spray dried potassium fluoride but not with other forms of this salt (Scheme 47) the E-ester was the major product with a stereoselectivity of 86—96%. 

Hu et al. developed a system that involved cooperative catalysis by a chiral phosphoric acid and an achiral rhodium complex (Scheme 3.37) [81]. They applied the binary catalytic system to a three component coupling reaction among a diazoesters, primary alcohols, and aldimines. The steric bulkiness of the primary alcohol had a significant effect on both diastereo and enantioselectivities. The sterically demanding 9 anthracenemethanol was the best component to give p amino a alkoxy esters with excellent stereoselectivities under the combined and cooperative catalysis by phosphoric acid ll and the rhodium complex. 

There are few examples of the reactions of alkenes with diazoesters of chiral alcohols which give high face discrimination in rhodium-catalyzed reactions [936, 1497). However, Davies and coworkers [192, 193, 1503] have performed the reactions of alkenes with vinyldiazoesters of chiral alcohols under Rh2(OAc)4 or better yet Rh2(OCOC7H j 5)4 catalysis. The ester of (K)-pantolactone 1.16 is the most efficient substrate, and ftum-cyclopropanecarboxylates are obtained highly selectively. Starting from 7.141 (R = Ph), the enantioenriched plant hormone l-amino-2-phenylcyclopropanecarboxylic acid has been prepared (Figure 7.88). 

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