HeteroCycles

Special Issue

Albert I. Meyers's Special Issues, Vol. 58, No. 1, 2002

66 data found. 61 - 66 listedFirst Previous

Paper | Special issue | Vol 58, No. 1, 2002, pp.601-634
Published online:

DOI: 10.3987/COM-02-S(M)60

■ Thiazoline Ring Formation from 2-Methylcysteines and 2-Halomethylalanines

Brant L. Kedrowski and Clayton H. Heathcock*

*Department of Chemistry, University of California, Berkeley, California 94720, U.S.A.

Abstract

A systematic survey of conditions and substrates for the formation of 2,4,4-trisubstituted thiazoline rings is presented. The substitution patterns of these thiazolines is particularly relevant for the synthesis of the tantazole, mirabazole, and thiangazole classes of natural products, which contain a linear array of these heterocycles. Methods for the formation of these thiazolines from 2-methyl cysteines and 2-halomethylalanines are discussed.

Note | Special issue | Vol 58, No. 1, 2002, pp.635-643
Published online:

DOI: 10.3987/COM-02-S(M)25

■ An Efficient Synthesis of a Key Intermediate for Vasopressin V₂ Receptor Agonist OPC-51803 by Lipase-catalyzed Enantioselective Transesterification

Tadaaki Ohtani, Kazuyoshi Kitano,* Jun Matsubara, Seiji Morita, Yoshikazu Kawano, Makoto Komatsu, Masahiko Bando, Masaru Kido, Minoru Uchida, and Fujio Tabusa

*Medical Chemistry Research Institute, Otsuka Pharmaceutical Co., Ltd., Kagasuno 463-10, Kawauchi-cho, Tokushima, Tokushima 771-0192, Japan

Abstract

An efficient and enantioselective synthesis of (R)-[1-(p-toluenesulfonyl)-2,3,4,5-tetrahydro-1H-1-benzazepin-5-yl]acetic acid (2), a key intermediate in the synthesis of (R)-2-{1-[2-chloro-4-(1-pyrrolidinyl)benzoyl]-2,3,4,5-tetrahydro-1H-1-benzazepin-5-yl}-N-isopropylacetamide (OPC-51803, 1), was accomplished. The chiral alcohol [(S)-3], the precursor of (R)-2, was separated from the racemic alcohol [(±)-3] using the lipase mediated transesterification in vinyl acetate. The obtained (S)-3 was fractionated without using column chromatography and it was converted to 2 without a decrease in the enantiomeric excess.

Note | Special issue | Vol 58, No. 1, 2002, pp.645-654
Published online:

DOI: 10.3987/COM-02-S(M)50

■ Asymmetric Trimethylsilylcyanation of Acetophenone Catalyzed by Cinchona Alkaloids

Michael C. K. Choi, Shu-Sun Chan, Man-Kong Chan, Jong Chul Kim, and Kiyoshi Matsumoto*

*Graduate School of Human and Environmental Studies, Kyoto University, Yoshida-Nihonmatsu-cho, Sakyo-ku, Kyoto 606-8501, Japan

Abstract

Six cinchona alkaloids were used as catalysts for the study of addition of TMSCN to acetophenone (1) at atmospheric and pressurized conditions. Only the about 10% ee was attained either in hexane or ethyl acetate using quinine or cinchonine. The enantiomeric excesses (ee’s) of the cyanohydrin (3) were found to be decreased with pressure in the presence of alkaloids. The rationale of these reactions was discussed.

Note | Special issue | Vol 58, No. 1, 2002, pp.655-658
Published online:

DOI: 10.3987/COM-02-S(M)55

■ A Concise Synthesis of a Potential Key Intermediate for 12-epi-Mycalamide A

Marcellino Rudyanto, Masahiro Toyota,* Natsuko Kagawa, and Masataka Ihara*

*Department of Organic Chemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Aobayama, Sendai 980-5878, Japan

Abstract

Intramolecular nitrile oxide cycloaddition (INOC) reaction of the oximes (7) provides the isoxazoline (9), a possible key intermediate for 12-epi-mycalamide A (2).

Note | Special issue | Vol 58, No. 1, 2002, pp.659-666
Published online:

DOI: 10.3987/COM-02-S(M)63

■ Multicomponent Reactions: Synthesis of Spirocyclic Tetrahydropyran Derivatives by Prins Cyclization

Arun K. Ghosh,* Dongwoo Shin, and Gary Schiltz

*Department of Chemistry, University of Illinois at Chicago, 845 West Taylor St., Chicago, IL 60607-7061, U.S.A.

Abstract

Substituted spirocyclic tetrahydropyranyl mesylates and tosylates have been synthesized in good yields using a Prins-type cyclization of various cyclic ketones, a homoallylic alcohol and either methanesulfonic or p-toluenesulfonic acid under non-aqueous conditions. The mesylates thus produced could then be transformed into the corresponding Boc-protected amines using an efficient two step procedure.

Review | Special issue | Vol 58, No. 1, 2002, pp.667-682
Published online:

DOI: 10.3987/REV-02-SR(M)1

■ **Nitrogen-containing Heterocycles via Palladium-catalyzed Reaction of Alkynes with Organic Halides or Triflates**

Sandro Cacchi,* Giancarlo Fabrizi, and Luca M. Parisi

*Dipartimento di Studi di Chimica e Tecnologia delle Sostanze Biologicamente Attive, Università degli Studi di Roma “La Sapienza”, Piazzale Aldo Moro 5, 00185 Roma, Italy

Abstract

The construction of nitrogen-containing heterocycles promoted by the reaction of alkynes with organic halides or triflates in the presence of palladium catalysts is reviewed.

66 data found. 61 - 66 listedFirst Previous