Solid-Phase Synthesis of Decalin Scaffolds by Robinson Annulation

Significance

The solid-phase construction of a decalin framework bearing an ester unit was described. Immobilized β-keto esters 2 and 3 as analogues of the Nazarov reagent were prepared in three steps from butynediol 1. The solid-phase Robinson-type annulation was performed with 3 and four kinds of enamines 4 in the presence of NaOMe or DBU as a base to give the corresponding polymer-bound decalin 5. The desired condensation products 6 were readily obtained via TBAF-mediated cleavage from the polymeric carrier in 28-37% yield as single diastereoisomers (de > 98%).