Rhodium-catalyzed cascade oxidative annulation leading to substituted naphtho[1,8-bc]pyrans by sequential cleavage of C(sp2)-H/C(sp3)-H and C(sp2)-H/O-H bonds.
J Am Chem Soc
; 134(39): 16163-6, 2012 Oct 03.
Article
em En
| MEDLINE
| ID: mdl-22989331
ABSTRACT
The cascade oxidative annulation reactions of benzoylacetonitrile with internal alkynes proceed efficiently in the presence of a rhodium catalyst and a copper oxidant to give substituted naphtho[1,8-bc]pyrans by sequential cleavage of C(sp(2))-H/C(sp(3))-H and C(sp(2))-H/O-H bonds. These cascade reactions are highly regioselective with unsymmetrical alkynes. Experiments reveal that the first-step reaction proceeds by sequential cleavage of C(sp(2))-H/C(sp(3))-H bonds and annulation with alkynes, leading to 1-naphthols as the intermediate products. Subsequently, 1-naphthols react with alkynes by cleavage of C(sp(2))-H/O-H bonds, affording the 12 coupling products. Moreover, some of the naphtho[1,8-bc]pyran products exhibit intense fluorescence in the solid state.
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Coleções:
01-internacional
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MEDLINE
Idioma:
En
Ano de publicação:
2012
Tipo de documento:
Article