A new efficient synthesis of polysubstituted 3,4-dihydroquinazolines and 4-3,1-benzothiazines via sequential Passerini/Staudinger/aza-Wittig/addition/nucleophilic substitution reaction has been developed. The three-component Passerini reactions of 2-azidobenzaldehydes , benzoic acid (), and isocyanides produced the azide intermediates , which were treated sequentially with triphenylphosphine, isocyanates (or CS), and secondary amines to give polysubstituted 3,4-dihydroquinazolines and 4-3,1-benzothiazines in good overall yields through consecutive Passerini/Staudinger/aza-Wittig/addition/nucleophilic substitution reactions.
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| http://dx.doi.org/10.3762/bjoc.18.32 | DOI Listing |
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