A tandem Petasis-Ugi multi component condensation reaction: solution phase synthesis of six dimensional libraries

Published in: Journal, Volume : 44, Issue : 3, Pages : 603-605

DOI : 10.1016/s0040-4039(02)02619-9

Author : Portlock, David E.; Ostaszewski, Ryszard; Naskar, Dinabandhu; West, Laura

Abstract : Amino acids with three points of diversity generated from the Petasis boronic acid-Mannich reaction can be used as one of the four components of the Ugi condensation to prepare six dimensional libraries of dipeptide amides. Thus, petasis amino acid substrate Me2NCH2CO2H underwent Ugi reaction with p-MeC6H4CH2NH2, PhCH2CH2CHO, and 2,6-Me2C6H3NC to afford 42% Me2NCH2CON(CH2C6H4Me-p)CH(CH2CH2Ph)CONHC6H3Me2-2,6.

A simple method for the preparation and selective functionalization of 4,5-diaminopyrazoles

Published in: Journal, Volume : 44, Issue : 14, Pages : 3009-3011

DOI : 10.1016/s0040-4039(03)00398-8

Author : Blass, Benjamin E.; Srivastava, Anil; Coburn, Keith R.; Faulkner, Amy L.; Seibel, William L.

Abstract : A simple procedure for the synthesis and further functionalization of 4,5-diaminopyrazoles using mild conditions is reported herein. The desired products were obtained in good yield, and the structures were confirmed by X-ray crystallog.

Applications of solid supported azide anion. A one-pot, two-step preparation of functionalized 1,2,3-triazoles

Published in: Journal, Volume : 44, Issue : 10, Pages : 2153-2155

DOI : 10.1016/s0040-4039(03)00180-1

Author : Blass, Benjamin E.; Coburn, Keith R.; Faulkner, Amy L.; Seibel, William L.; Srivastava, Anil

Abstract : Functionalized 1,2,3-triazoles were prepared in a one-pot, two-step synthesis from alkyl halides and alkynes using a polymer supported azide. Two different base resins were examined The chem. is suitable for the preparation of combinatorial libraries.

Solid-phase synthesis of functionalized 1,2,4-triazin-6-ones

Published in: Journal, Volume : 43, Issue : 45, Pages : 8165-8167

DOI : 10.1016/s0040-4039(02)01956-1

Author : Blass, Benjamin E.; Coburn, Keith R.; Faulkner, Amy L.; Liu, Song; Ogden, Adam; Portlock, David E.; Srivastava, Anil

Abstract : The solid supported synthesis of functionalized 1,2,4-triazin-6-ones from resin bound amino acids and acid chlorides is described. A thioamide intermediate is generated with Lawesson’s reagent, and the final products are cyclized and cleaved from resin with hydrazine. The products are obtained in good yield and purity.

Petasis boronic acid-Mannich reactions of substituted hydrazines: synthesis of α-hydrazino carboxylic acids

Published in: Journal, Volume : 43, Issue : 38, Pages : 6845-6847

DOI : 10.1016/s0040-4039(02)01511-3

Author : Portlock, David E.; Naskar, Dinabandhu; West, Laura; Li, Min

Abstract : R1CONHNHR2 [R1 = OCMe3, OCH2Ph, NH2; R2 = cyclohexylmethyl, Me2CHCH2, MeO2CCH2, PhCH2, Ph, 4-MeC6H4, 4-O2NC6H4,2-pyridyl, H, EtO2CCH2] can serve as amine substrates for the Petasis boronic acid-Mannich reaction with R3B(OH)2 [R3 = 4-MeOC6H4, 4-MeC6H4, PhCH:CH, Ph, 2-benzothienyl, 1-naphthyl] and OCHCO2H, providing a practical synthetic route for the preparation of α-hydrazinocarboxylic acids R1CONHNR2CHR3CO2H. The scope and limitations of this method have been examined

Solution phase synthesis of imidazo[1,2-b]pyrazol-2-one, an interesting 5,5-fused heterocyclic ring system

Published in: Journal, Volume : 45, Issue : 3, Pages : 619-621

DOI : 10.1016/j.tetlet.2003.10.177

Author : Blass, Benjamin E.; Srivastava, Anil; Coburn, Keith R.; Faulkner, Amy L.; Janusz, John J.; Ridgeway, James M.; Seibel, William L.

Abstract : The solution phase synthesis of a series of imidazo[1,2-b]pyrazol-2-ones, e.g., I, a fused 5,5-ring system, is described. The heterocyclization of α-hydrazino acids with α-cyano ketones gave 5-aminopyrazoles, e.g., II, which underwent an intramol. cyclodehydration to give the corresponding imidazo[1,2-b]pyrazol-2-ones.