H. Franzyk et al., Conversion of the iridoid glucoside antirrhinoside into 3-azabicyclo[3.3.0]octane building blocks, J NAT PROD, 63(5), 2000, pp. 592-595
The iridoid glucoside antirrhinoside (1) was transformed into polysubstitut
ed 3-azabicyclo[3.3.0]octanes 3, 12, and 13 in 4 to 5 steps. Ozonolysis of
the diacetonide of 1 and of its 7-deoxy-derivative 8 afforded cyclopentanoi
ds 2 and 10, respectively. Conditions for the selective conversion of 2 and
10 into the corresponding ditosylates 4 and 11 were investigated. Cyclizat
ion of 4 and 11 was achieved with benzylamine and 2-methoxybenzylamine to y
ield bicyclic pyrrolidines 3, 12, and 13. Additional building blocks 14 and
15 were obtained by selective deprotection of the N-benzyl and isopropylid
ene moieties in 12 and 13, respectively.