Hydroformylation of Internal Alkenes by Encapsulated Rhodium

Significance This is an outstanding report with unprecedented regioselectivity for hydroformylation of internal alkenes. The use of encapsulated rhodium gives extremely high regioselectivity, whereas a standard rhodium catalyst (not encapsulated) gives nearly a 1:1 mixture of isomers. When the reaction is performed at 25 °C, the highest regio­selectivity is obtained, and the selectivity decreases with an increase in temperature due to isomerization pathways capable at the elevated temperatures.