Steven A. Weissman
Merck & Co.
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Featured researches published by Steven A. Weissman.
Organic Letters | 2009
James Z. Deng; Daniel V. Paone; Anthony Ginnetti; Hideki Kurihara; Spencer D. Dreher; Steven A. Weissman; Shaun R. Stauffer; Christopher S. Burgey
The palladium-catalyzed Suzuki-Miyaura reaction has been utilized as one of the most powerful methods for C-C bond formation. However, Suzuki reactions of electron-deficient 2-heterocyclic boronates generally give low conversions and remain challenging. The successful copper(I) facilitated Suzuki coupling of 2-heterocyclic boronates that is broad in scope is reported. Use of this methodology affords greatly enhanced yields of these notoriously difficult couplings. Furthermore, mechanistic investigations suggest a possible role of copper in the catalytic cycle.
Tetrahedron Letters | 1995
Kai Rossen; Steven A. Weissman; J. Sager; Robert A. Reamer; David Askin; Ralph P. Volante; Paul J. Reider
Abstract Hydrogenation of tetrahydropyrazine 4g with [(R)-BINAP(COD)Rh]TfO gave piperazine 6g in 96% yield and 99% ee. Simple hydrogenolytic deprotection and crystallization afforded the key chiral (S)-N-Boc-piperazine MK-639 intermediate 1 in high yield and enantiomeric purity.
Tetrahedron Letters | 1993
Joseph Auerbach; Steven A. Weissman; Thomas J. Blacklock; Marshall R. Angeles; Karst Hoogsteen
A new bromination method employing NBS or dibromodimethylhydantoin in aqueous base is described for the synthesis of 3-bromo-2,6-dimethoxybenzoic acid (1) and other monobrominated alkoxybenzoic acids.
Tetrahedron Letters | 2001
Jaemoon Lee; Thoa Hoang; Stephanie Lewis; Steven A. Weissman; David Askin; Ralph P. Volante; Paul J. Reider
Abstract A catalytic highly enantioselective (99% ee) preparation of N - tert -butyloxycarbonyl-(2 S ,3 S )-3-hydroxy-2-phenyl-piperidine and N - tert -butyloxycarbonyl-(2 S )-2-phenyl-piperidin-3-one was developed using an intramolecular epoxide opening followed by ring expansion. The cis -epoxide starting material was available in high ee via Jacobsen epoxidation.
Chemistry: A European Journal | 2002
Philip J. Pye; Kai Rossen; Steven A. Weissman; Ashok Maliakal; Robert A. Reamer; Richard G. Ball; Nancy N. Tsou; Ralph P. Volante; Paul J. Reider
A novel three-component condensation followed by a crystallization-induced asymmetric transformation is used to build this key substance P inhibitor intermediate in a short synthetic sequence.
Tetrahedron | 2001
Atsushi Akao; Shouichi Hiraga; Takehiko Iida; Asayuki Kamatani; Masashi Kawasaki; Toshiaki Mase; Takayuki Nemoto; Nobuya Satake; Steven A. Weissman; David M. Tschaen; Kai Rossen; Daniel E. Petrillo; Robert A. Reamer; Ralph P. Volante
Abstract DNA topoisomerase I inhibitors are currently under investigation as cancer chemotherapy agents of which indolocarbazole glycoside ( 1 ) has been identified as a promising candidate. A practical, scalable synthesis of 1 that limits the isolation of cytotoxic compounds to only that of the final product is described. The convergent process features a novel phase transfer-promoted glycosylation of aglycone core ( 4 ); subsequent hydrolysis provides anhydride ( 8 ). The hydrazine fragment ( 3 ), which is coupled with 8 , is synthesized via a modification of existing procedures. The coupled product ( 2 ) is subsequently hydrogenated to provide 1 in excellent purity via direct crystallization (>99.3 A%).
Tetrahedron | 1996
Peter E. Maligres; Steven A. Weissman; Veena Upadhyay; Steven J. Cianciosi; Robert A. Reamer; Robert Purick; Jess W. Sager; Kai Rossen; Kan K. Eng; David Askin; Ralph P. Volante; Paul J. Reider
Abstract Reaction of 2-alkyl-4-enamides with 1 + and aqueous sodium bicarbonate results in the diastereoselective formation of the corresponding iodohydrins with essentially no iodolactone by-product. The reaction appears to proceed through a cyclic imidate type intermediate. This methodology has been successfully employed for the synthesis of the epoxide intermediate of the orally active HIV-1 protease inhibitor MK-639 (indinavir sulfate).
Tetrahedron Letters | 1998
Steven A. Weissman; Stephanie Lewis; David Askin; Ralph P. Volante; Paul J. Reider
Abstract A practical two pot synthesis of N -arylpiperazinones from the corresponding aniline is described. The key transformation is a selective intramolecular Mitsunobu cyclodehydration of an amidoalcohol intermediate. A series of N -arylpiperazinones were prepared in yields up to 89%.
Chemical Reviews | 1987
Steven A. Weissman
Journal of Organic Chemistry | 2005
Steven A. Weissman; Daniel Zewge; Cheng Chen