Highly Diastereoselective Hydrosilane‐Assisted Rhodium‐Catalyzed Spiro‐Type Cycloisomerization of Succinimide and Pyrazolone‐Based Functional 1,6‐Dienes

Organosilicon compounds are important reagents and synthetic intermediates that play a key role in the construction of new materials and complex products. Here we show a highly diastereoselective rhodium‐catalyzed cycloisomerization of 1,6‐dienes, in which the use of (EtO)3SiH accelerates the intramolecular cyclization reaction to afford a novel spiro‐fused succinimide and pyrazolone derivatives in moderate to excellent yields as a single diastereoisomer. The proposed mechanism involves an active Rh−H species from the hydrosilane that is the H‐donor in this spiro‐type cycloisomerization reaction. A highly diastereoselective rhodium‐catalyzed cycloisomerization of 1,6‐dienes that is promoted by hydrosilane has been established to afford spiro‐fused succinimide and pyrazolone derivatives in moderate to excellent yields as a single diastereoisomer.