Regio- and Stereoselective Ring-Opening Reactions of Chiral Substituted Spiro[2.4]hepta-4,6-dienes:  A New, Simple, and Versatile Approach to the Synthesis of Optically Active Bidentate Cyclopentadienyl−Phosphine Ligands. X-ray Crystal Structure of (S)-[Rh(η²-C₂H₄)(η⁵-C₅H₄CH₂CHPhPPh₂-κP)]

Abstract

The ring-opening reaction of (S)-1-phenylspiro- [2,4]hepta-4,6-diene with LiPPh 2 proceeds with full regio-and stereoselectivity, taking place at phenylsubstituted carbon and with complete inversion of the configuration at the stereogenic center, yielding (S)-[Li-(C 5 H 4 CH 2 CHPhPPh 2 )]. Optically active complexes of rhenium, rhodium, zirconium, and iron with this new chiral bidentate ligand have been prepared; additionally, the X-ray crystal structure of (S)-[Rh(η 2 -C 2 H 4 )(η 5 -C 5 H 4 -CH 2 CHPhPPh 2 -κP)] is reported.

Stable and Catalytically Highly Active ansa Compounds with Cycloalkyl Moieties as Bridging Units

“…Cyclopentanediol bis(methanesulfonate) was synthesized from 1,2-cyclopentanediol using published procedures. [8] SpiroA…”

“…Amongst these, ansa-type complexes, which had first been described by Eilbracht et al in the late 1970s, have aroused attention due to their potential applications in the field of asymmetric catalysis. [5][6][7][8] Herein the first representatives of a series of new molybdenum and tungsten ansa complexes with cycloalkyl moieties as exceptionally stable bridging units are described as is also the use of these complexes as catalysts for olefin epoxidation reactions at room temperature.…”

“…Reaction of cyclopentanediol bis(methanesulfonate) with sodium cyclopentadienide in THF was carried out following known reaction procedures [8] , and resulted in the novel spiro-annulated diene 1, which was then reacted with M(CO) 3 Mo NMR of compound 2a shows the molybdenum at d = À1388 ppm. This value is consistent with previously reported ansa-compounds.…”

A New Route to Cationic Half‐Sandwich Ruthenium(II) Complexes with Chiral Cyclopentadienylphosphane Ligands

“…[9] We have developed such a route by adapting the method first reported by Kauffmann, [14] which is based on the ring-opening reactions of spiro [2.4]hepta-4,6-dienes. [15] Traditionally, the spiro compounds have been synthesised by bis-alkylation of cyclopentadiene with the corresponding dibromoalkane in the presence of sodium amide or sodium hydride. [16] However, a more convenient approach to introduce chirality into these spiroannulated precursors is the use of the corresponding bis(mesylate)s or bis(tosylate)s as alkylating reagents.…”

New cyclopentadienylethylphosphane chelate complexes with unsymmetrical phosphane substitution

“…49 Similar to the formation of rac-5 and rac-6 the corresponding tert-butyl(cyclohexyl) substituted complexes rac-9 and rac-10 are obtained in moderate yields from spiro[2.4]hepta-4,6-diene [65][66][67][68] Cole-Hamilton et al, 69 Lalinde et al, 70 and Whitby et al…”