Ov. Gulyakevich et al., Stereoselectivity of the annelation of 3,4-dihydroisoquinolines by 5-monosubstituted 2-acylcyclohexane-1,3-diones, MENDELEEV C, (3), 1999, pp. 119-121
The annelation of 1-methyl-3,4-dihydroisoquinoline by prochiral 5-substitut
ed 2-acylcyclohexane-1,3-diones proceeds diastereoselectively yielding a 9R
,16R:9S,16S pair of enantiomers rather than a possible mixture of four 8-az
a-D-homogona-12,17a-dione stereoisomers; this stereoselectivity results fro
m the impossibility of a three-attack on the prochiral beta,beta'-triketone
by azomethyne owing to the spatial structure of 2-acylcyclohexane-1,3-dion
e, on the one hand, and by the steric effect of the C(1) methyl group of 3,
4-dihydroisoquinoline, on the other.