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

Abstract

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.

Catalytic Stereoselective Multicomponent Reactions for the Synthesis of Spiro Derivatives: Recent Progress

“… Synthesis of spiro‐clubbed succinimide and pyrazolone derivative reported by Li, Xu, and co‐workers [132] …”

“…In the final step, spiro products are formed by β-hydride elimination (Scheme 40). [132] Multicomponent cyclopropanation of dimethylsulfonium ylides and 2-arylidene-1,3-indanediones using triethylamine (Cat.31) in hexafluoroisopropanol (HFIP) developed by a team led by Xing, Wu, and Wang. This produces structurally interesting spiro-cyclopropane derivatives in excellent yields (up to 97 %) and also shows an excellent diastereomeric ratio (dr > 20 : 1).…”

“…Synthesis of spiro-clubbed succinimide and pyrazolone derivative reported by Li, Xu, and co-workers. [132] Scheme 41. Synthesis of spiro-cyclopropane reported by Xing, Wu, Wang, and co-workers.…”

“…This first section is organized by the type of Michael cascade cyclization reactions, i. e., Michael spiro‐cyclization, [94–98] Michael/ N ‐hemiketalization or alkylation reaction, [99–103] Michael–Michael aldol reaction, [104–107] double Michael addition cyclization reaction, [108–110] and oxa/aza Michael cascade reaction [111–113] . The second part of this review is devoted to stereoselective multicomponent cycloaddition reactions, [114–121] and the third section contains diastereoselective approaches [122–135] and some miscellaneous reactions [136–140] to form spiro‐hetero/carbocycles.…”