Nitroso regioselective synthesis

Scheme 1.31 Regioselective synthesis of N- or O-adduct in enantioselective Nitroso aldol reactions.

Pteridine syntheses from pyrimidine intermediates Traube synthesis and can be condensed with 1,2-dicarbonyl compounds and ketones and aldehydes, respectively, in a very effective manner. There is also a series of regioselective approaches leading towards 6- and 7-substituted pteridine derivatives carrying a broad variety of substituents in these positions. 

The dihydrooxazines which are produced from aryl nitroso compounds have not found wide use in synthesis. One application to the syntheses of an N-aiyl-3-pyrrolidone is shown in equation (31). The initial Diels-Alder reaction in this sequence was totally regioselective. 

The synthesis of tabtoxinine /3-lactam is briefly outlined in Scheme 3-XII. The initial nitroso formate cycloaddition was totally regioselective and provided the basic functionality needed to ultimately prepare 18. 

Stannyl enol ethers undergo the aldol-type reaction with nitroso compounds to give a-aminoxy ketones or a-hydroxylamino ketones (Scheme 3-196). Regioselective and enantioselective synthesis of a-hydroxy ketones and a-amino ketones is of great synthetic significance, as these are readily converted to a variety of heterocycles. -... 

---