Cyclization agents/cyclizations zinc acetate

The reductive cyclization of 2-nitrobenzyl-A, A -bis(formamide) with zinc in acetic acid to quinazoline was first described by RiedelT ° The reaction is used successfully for the synthesis of larger quantities of quinazoline and its benzene-ring-substituted derivatives 12 from 2-ni-trobenzyl-A, A -bis(formamides) 11. The method is suitable only for the preparation of 4-un-substituted quinazolines, because 2-nitro-substituted phenones do not condense with aliphatic amides to yield bis(amide) derivatives. Zinc in acetic acid is the reducing agent of choice, but iron in hydrochloric acid or Raney nickel can also be used. " Applications of compounds other than bis(formamides) [e.g., bis(acetamides) ] and preparation of 2-substituted quinazolines by Riedel s synthesis are scarce. 

Properties M.w. 184.31 sp.gr. 0.993-0.997 b.p. 95-97 C (13 mm Hg) ref. index 1.579 Toxicology TSCA listed Uses Reducing agent for prep, of silyl-substituted alkylidene complexes of tantalum, in ionic reduction of enones to sat. ketones, in reductive cyclization of unsat. ketones, for esters in presence of zinc hydride catalyst, for o-halo ketones in presence of Mo(0), reduction of thio esters to ethers, esters to alcohols with Rh catalysis, in assym. reduction of methyl ketones, reductive cleaving of allyl acetates Manuf./Distrib. ABCR http //www.abcr.de, Alfa Aesar http //www.aifa.com-. Digital Spec. Chems. http //www.digHaichem.com, Fluorochem USA... 

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