Nitroso-dienophile additions to dendralenes: a short synthesis of branched aminosugars
Ruomeng Wang1, Gomotsang Bojase, Anthony C Willis
1Australian Research Council Centre of Excellence for Free Radical Chemistry and Biotechnology, Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia.
Abstract:
The first heteroatom-based dienophile cycloadditions to cross-conjugated alkenes ([n]dendralenes) are reported. Nitroso-dienophiles undergo smooth single and double Diels-Alder additions to the parent dendralenes with orientational regio- and stereoselectivity and, notably, with reactivity that depends upon the parity of the [n]dendralene. The first crystal structure of a cross-conjugated hexaene is reported. Vasella's nitroso-sugar reagent gives a highly enantiomerically enriched double cycloadduct with [3]dendralene. This bicyclic oxazine is successively dihydroxylated and then ring-opened to form a branched chain diamino tetrol.
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