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Most Requested Journal Articles 2Q05-Chemistry and Related

Following is one of the journal articles most requested by researchers using CAS online services.

CAS indexed 51 chemical substances from this document.
CAS subject entries for this document include: Cycloaddition reaction; Crystal structure; Molecular structure; and 3 additional concepts.

TITLE:	Total Synthesis of (-)-7-Epicylindrospermopsin, a Toxic Metabolite of the Freshwater Cyanobacterium Aphanizomenon ovalisporum, and Assignment of Its Absolute Configuration
AUTHOR(S):	White, James D.; Hansen, Joshua D.
CORPORATE SOURCE:	Department of Chemistry, Oregon State University, Corvallis, OR, 97331-4003, USA
SOURCE:	Journal of Organic Chemistry (2005), 70(6), 1963-1977 CODEN: JOCEAH; ISSN: 0022-3263
PUBLISHER:	American Chemical Society
LANGUAGE:	English

ABSTRACT:
The Z and E nitrones II, prepd. from condensation of the corresponding aldehyde and hydroxylamine, underwent intramol. dipolar cycloaddn. to give substituted 1-aza-7-oxobicyclo[2.2.1] heptanes. Reductive N-O bond cleavage followed by carbonylation gave the cyclic urea in which inversion of the secondary alc. was effected via an oxidn.-redn. sequence. After conversion of the p-bromobenzyl ether to the azide, activation of the cyclic urea as its O-methylisourea and redn. of the azide led to spontaneous cyclization to afford the tricyclic nucleus of cylindrospermopsin. Global deprotection, including hydrolysis of the 2,4-dimethoxypyrimidine appendage to a uracil, and then monosulfation of the resultant diol afforded a substance identical with natural (-)-7-epicylindrospermopsin (I). The asym. synthesis of (-)-7-epicylindrospermopsin defines its abs. configuration as 7S,8R,10S,12S,13R,14S.

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Updated 5/8/2007 10:33:08 AM