Hsu YC, Ting CM, Liu RS. Stereocontrolled synthesis of complicated oxacyclic compounds via platinum-catalyzed [4 + 2]-cycloadditions and annulations of enynals with allylic alcohols.
J Am Chem Soc 2009;
131:2090-1. [PMID:
19161254 DOI:
10.1021/ja809560c]
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Abstract
We report stereoselective synthesis of tricyclic ketals through Pt(II)-catalyzed [4 + 2]-cycloaddition of benzopyrilium/1-en-3-ol functionalities. For nonaromatic enynals, we obtained distinct tricyclic oxacyclic ketones due to occurrence of a new annulation reaction. This work reports the first example that [4 + 2]-cycloadducts are successfully intercepted from such functionalities in diversified approaches. The value of such cycloadditions and annulations are shown by their high diastereoselectivities and chemoselectivities.
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