Toward the synthesis of cobyric acid. Enantioselective syntheses of completely differentiated ring D synthons

Organic Letters

Volumn 10, Issue 13, 2008, Pages 2837-2840

  Wang, Hui ^a   Tassa, Carlos ^a   Jacobi, Peter A ^a  

^a Dartmouth College   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ACID; COBYRIC ACID; CYANOCOBALAMIN; DRUG DERIVATIVE; PYRROLE DERIVATIVE; PYRROLINE;

ARTICLE; CHEMICAL STRUCTURE; CHEMISTRY; STEREOISOMERISM; SYNTHESIS;

ACIDS; MOLECULAR STRUCTURE; PYRROLES; STEREOISOMERISM; VITAMIN B 12;

EID: 51649085345     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol800985m     Document Type: Article

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16. 2.
17. The low reactivity of Z-22a and -b is surprising, since numerous examples of selective β-coupling of cyclic α,β-dibromoenones are known. See, for example: Pelphrey, P. M.; Orugunty, R. S.; Helmich, R. J.; Battiste, M. A.; Wright, D. L. Eur. J. Org. Chem. 2005, 4926.
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20. These studies were initially carried out with racemic (±)-20b.
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22. The structure of the predominate (S)-relative epimer was confirmed by X-ray analysis of a racemic sample (cf. ref 16). We thank the University of Massachusetts Amherst X-ray Structural Characterization Facility (NSF CHE 9974648) for providing diffractometer access and Mr. Travis Benanti of that facility for data collection and refinement.
23. A reviewer commented that the term "synthon" as originally defined referred to an abstract entity arising from a retrosynthetic analysis (typically a radical, cation or anion). Presently, though, this term is more commonly associated with synthetic precursors or "equivalents".