Efficient new syntheses of (+)and (-)-anatoxin-a. Revised configuration of resolved 9-methyl-9-azabicyclo[4.2.1]nonan-2-one

Article abstract of DOI:10.1016/0040-4039(95)01842-6

The bicyclic ketone 2, as either enantiomer, was converted in high yield to the glycidonitrile 4 by successive base-catalysed condensation with 2-chloropropionitrile and N-dealkylation. Opening of the epoxide followed by elimination of HCl from the resulting α-chloroketone gave the enone 7 which was converted to anatoxin-a 1 by mild acidolysis. Maintenance of chiral homogeneity from both (+)- and (-)2 was demonstrated by diastereomeric amide formation from (+)- and (-)-1. However, the prior correlation of (+)- 2 with (+)- 1 was found to be incorrect; in fact (-)- 2 gives (+)- 1.