Organometallic Derivatives of Cyclopropanes and their Reactions

Abstract

Introduction Metal Derivatives of Cyclopropane Cyclopropylidene Complexes Metal Derivatives of Cyclopropene η 3 ‐Cyclopropenyl Complexes (Metallatetrahedranes) Cyclopropenylidene Complexes Metal Derivatives of Methylenecyclopropane Methylenecyclopropene Complexes (Triafulvenes) Acknowledgments

Cyclopropanation

“…Although ruthenium catalysts are newcomers compared to their copper and rhodium counterparts, their exceptional reactivities and stereoselectivities have made them popular. Although early results, with low yield (38%) of cyclopropane from styrene and EDA, from the ruthenium cyclopropanation catalyst Ru 2 (OAc) 4 Cl was not exciting (30), more than 10 years later more efficient cyclopropanation catalysts of ruthenacarborane cluster were developed to give good yields of cyclopropane from a number of different aryl and alkyl alkenes with EDA (31). A diruthenium(II) tetracarboxylate catalyst ([Ru 2 (µ-CF 3 COO) 4 ]) that is a structural analogue of dirhodium(II) tetracarboxylate gave quantitative yield of cyclopropane from cyclooctene and EDA, but the reaction had to be performed at 60 • C (32).…”

“…[2+1]Cycloaddition of 1-seleno-2-silylethene to vinyl ketones in the presence of a chiral Lewis acid catalyst derived from TiCl 4 , Ti(OiPr) 4 , and chiral 1,1 -binaphthol (BINOL) gave enantiomerically enriched cis-cyclopropanes (Scheme 22) (110). The proposed reaction pathway was via silicon migration and ring closure with the aid of selenium coordination.…”

“…In the early stage of developing rhodium catalysis for intramolecular cyclopropanation, Rh 2 (OAc) 4 was widely used in the construction of bridged or fused polycyclic molecules. For instance, it was used as a catalyst to obtain a tricyclic ketone used as an intermediate of eucalyptol in good yield (Scheme 23) (111).…”

“…The major advancement occurred when rhodium(II) carboxamidates 20 were introduced. In particular, Rh 2 (5S-MEPY) 4 catalyst 37 gave high enantiocontrol or regioselective intramolecular cyclopropanation of different allyl diazoacetates and diazoacetamides (Scheme 24). With simple allyl diazoacetates (R 1 and R 2 = H), good yields and high enantiocontrols of the 3-oxabicyclo[3.1.0]hexan-2-ones were obtained even when the catalyst concentration as low as 0.1 mol% was employed (114).…”

“…Cyclopropanes with their three carbon atoms constitute the smallest member of the cycloalkane family and have attracted much attention from various disciplines (1)(2)(3)(4). Cyclopropanes are found as structural elements in many naturally occurring products useful for their insecticidal, antimicrobial, and antifungal activities (5).…”