Benzyl isocyanoacetate, pyrrole synthesis

Benzyl isocyanoacetate is a nsefnl reagent for the preparadon of benzyl 5-nnsnbsdnited pyrrole-2-carboxylates, which are widely used In the synthesis of porphyrins." Ono and coworkers have prepared pyrroles snbsdnited with various snbsdnients at the fi-posidons."" Because the reqidsite fi-nitro acetates for nitroalkenesi are readily available by the Henry... 

Several new examples of the Barton-Zard pyrrole synthesis from nitroalkenes and isocyanoacetate esters demonstrate the broad utility of this procedure. An excellent yield of ethyl 3-(9-anthryl)-4-ethylpyrrole-2-carboxylate was obtained starting with the nitroalkene from anthracene-9-carboxaldehyde and 1-nitropropane. <95TL8457> Bums et.al. reported an improved synthesis of benzyl isocyanoacetate which facilitates the synthesis of benzyl pyrrole-2-carboxylate esters by this method. <95SC379> 3-(l-Arylpyrrol-2-yl)pyrrole-2-carboxylates were prepared from l-aryl-2-(nitrovinyl)pyrroles. <95JHC 1703>... 

Ono, N., Katayama, H., Nisyiyama, S., Ogawa, T. Regioselective synthesis of 5-unsubstituted benzyl pyrrole-2-carboxylates from benzyl isocyanoacetate. J. Heterocycl. Chem. 1994, 31,707-710. 

Tosylmethyl isocyanide (TosMIC) was employed in a key step for the synthesis of bicyclic heterocycles from L-glutamic acid <01H(55)2099>, while benzyl isocyanoacetate was utilized for reaction with a-acetoxynitro compound 41 to yield the pyrrole 42, an intermediate in the synthesis of (+)-deoxypyrro oline, a putative cross-link of bone collagen <01JOC11>. 

Gribble and Pelkey adapted the Barton-Zard pyrrole synthesis [84] to 3-nitroindoles and ethyl isocyanoacetate (and tosylmethyl isocyanide) to give 2,4-dihydropyrrolo [3,4-T [indoles (Scheme 15, equation 1) [85, 86], In complementary work, Gribble and cowoikers synthesized pyrrolo[3,4-fc]indoles from the 1,3-dipolar cycloaddition of 2- and 3-nitroindoles with miinchnones (1,3-oxazo-lium-5 elates) (eqnations 2, 3) [87, 88]. The mesoionic miinchnones were generated in situ from the appropriate Af-benzyl-Af-acylamino acids. Gribble and Kishbaugh... 

Caldarelli et al. (240) have recently reported a five-step synthesis of substituted p)Trole libraries L22 and L23 using solid-supported reagents and scavengers. The synthesis involved oxidation of benzyl alcohols Mi to aldehydes (step a, Fig. 8.46), Henry reaction of aldehydes 8.91 with nitroalkanes M2 (step b), and acylation and elimination of nitroalcohols 8.93 (steps c and d) to give the nitrostyrenes 8.94, which were subjected to 1,3-dipolar cycloaddition with an isocyanoacetate (step e) to give the pyrroles 8.95. N-alkylation of these pyrroles with alkyl halides (step f) and final library-from-a-library hydrolysis/decarboxylation of L22 gave a library of trisub-stituted pyrroles L23 (step g. Fig. 8.46). 

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