24342-04-9Relevant articles and documents
Reactions of Carbonyl-Conjugated Alkynes with N-Bromosuccinimide and N-Iodosuccinimide in DMF/H2O and Methanol/Sulfuric Acid: Syntheses of Dihalo Diketones, Dihalo Ketoesters, and Dihalo Acetals
Heasley, Victor L.,Shellhamer, Dale F.,Chappell, Alfred E.,Cox, Jason M.,Hill, David J.,McGovern, Shanna L.,Eden, Cyndi C.,Kissel, Charles L.
, p. 4433 - 4437 (1998)
The following terminal, carbonyl-conjugated alkynes were reacted with N- bromosuccinimide (NBS) and N-iodosuccinimide (NIS) in MeOH/H2SO4 to give dibromo and diiodo acetals in the indicated yields: 3-butyn-2-one, 1: NBS (75%), NIS (95%); 1-phenyl-1-propyn-l-one, 2: NBS (90%), NIS (40%); 1-hexyn-3-one, 3: NBS (90%), NIS (70%); methyl propiolate, 4: NBS (20%, not isolated), NIS (95%). 4,4-Dimethyl-l-pentyn-3-one (5) gave only a trace of dibromo acetal and no diiodo acetal; tribromide and tetrabromide were the major products. NBS and NIS reactions required, respectively, 20% and 33 wt % of H2SO4. The reaction was unsuccessful with internal alkynes 4-phenyl-3-butyn-2-one and 3-hexyn-2-one which gave only complex mixtures of products. Alkyne 2 gave a significant yield of acetal-ketal in addition to the dihalo acetals. Both the dibromo acetal- ketal and diiodo acetal-ketal were isolated, but only the former could be hydrolyzed to the dibromo acetal. Internal, carbonyl-conjugated alkynes reacted with NBS and NIS in H2O/DMF (40:60) to give the following products in the indicated yields: 4-phenyl-3-butyn-2-one (6): 1-phenyl-3,3- dibromo-1,3-butanedione (17, 70%), 1-phenyl-3,3-diiodo-1,3-butanedione (21, 95%); 3-hexyn-2-one (7): 3,3-dibromo-2,4-hexanedione (18, 80%), 3,3-diiodo-2,4-hexanedione (22, 95%); methyl 3- phenyl-2-propynoate (8): methyl 2,2-dibromo-3-keto-3-phenylpropanoate (19, 43%), methyl 2,2- diiodo-3-keto-3-phenylpropanoate (23, 95%); methyl 2-pentynoate (9): methyl 2,2-dibromo-3- ketopentanoate (20, 80%), methyl 2,2-diiodo-3-ketopentanoate (24, 95%). All reactions, except for 6 and 8 with NBS, required H2-SO4. The terminal, carbonyl-conjugated alkyne, 3-butyn-2-one, did not give products, possibly because of oxidation of the intermediate aldehyde by NBS and NIS. Mechanisms involving electrophilic attack by halogen on the triple bond and an acid-catalyzed mechanism are discussed.
Copper-Catalyzed Domino Synthesis of Benzo[4,5]imidazo[1,2-a]pyrimidin-4(10H)-ones using Cyanamide as a Building Block
Lou, Zhenbang,Wu, Xudong,Yang, Haijun,Zhu, Changjin,Fu, Hua
supporting information, p. 3961 - 3968 (2016/01/25)
An efficient and practical copper-catalyzed domino synthesis of benzo[4,5]imidazo[1,2-a]pyrimidin-4(10H)-ones has been developed. The protocol uses N-(2-halophenyl)-3-alkylpropiolamides and cyanamide as the starting materials, inexpensive copper(I) iodide and pipecolinic acid as the catalyst and ligand, and the corresponding products were obtained in moderate to good yields.
One-pot synthesis of trisubstituted monomethylated benzene-1,3-diols via a Michael addition-Dieckmann cyclization sequence from methyl (E)3-methoxy-4- methoxycarbonylbut-2-enoate anion and methyl alkynoates and its application to the total synthesis of nidulol
Covarrubias-Zuniga, Adrian,San German-Sanchez, Laura,Maldonado, Luis A.,Romero-Ortega, Moises,Avila-Zarraga, Jose G.
, p. 2293 - 2296 (2007/10/03)
The reaction of methyl (E)3-methoxy-4-methoxycarbonylbut-2-enoate (1) with a number of methyl alkynoates under appropriate conditions gave the monomethylated trisubstituted resorcinol derivatives 3 in a regiocontrolled manner, via a Michael addition-Dieckmann cyclization sequence in one pot. The resorcinol 3d, prepared in this manner, was used as the starting material for a three step, highly efficient (54% from 3d) synthesis of the bioactive fungal metabolite nidulol (4). Georg Thieme Verlag Stuttgart.
