Stereoselective synthesis of alcohols. Part LV. Domino hydroformylation-allylboration-hydroformylation reactions to give trans-perhydropyrano[3,2-b]pyridine derivatives

N-Allyl-(E)-γ-aminoallyl boronates 8 and 18, when subjected to hydroformylation conditions, enter into a domino hydroformylation-allylboration-hydroformylation reaction cascade to generate the bicyclic N,O-heterocycles 12 and 20. On reaction of the methallyl compound 8b a stereogenic center is generated in the initial hydroformylation, which controls the relative configuration of the two new stereogenic centers resulting from the allylboration reaction.