Enantioselective cyclopropane synthesis using the chiral carbene complexes (SFeSC)- and (RFeSC)-(C5H5)(CO)(Ph2R*P)Fe:CHCH3+ (R* = (S)-2-methylbutyl). Role of metal vs. ligand chirality in the optical induction

Abstract

6721 Scheme I11 CI I I CHzCI2 + C u C I / P ( O E t ) 3 hr CICH2-Cu-CI P(OEtI3 CICH,;(OEt ) 3 C I --t CUCl I CICH2PO(OEt)z 4-E t C l 2 acrylate may also be explained reasonably by a similar two electron oxidative addition-reductive elimination pathway (Scheme 111). 2 was not obtained without assistance of photoirradiation or in a photochemical reaction without CuCl catalyst. The reactions of Scheme I1 and I11 further suggest that pathway a and not b of Scheme I is involved in copper(1)-catalyzed photoaddition of alkyl halides to olefins. Acknowledgment. This work was supported by a Grant-in-Aid for Scientific Research (No. 56550606) from the Ministry of Education, for which we are grateful. Registry No. CH,(CH,),Br, 109-65-9; c-C6Hl,Br, 108-85-0; (C-H,),CBr, 507-19-7; Br(CH,),Br, 110-52-1; Br(CH,),Br, 109-64-8; Br-(CH,),Br, 106-93-4; Br(CH,),COOEt, 539-74-2; CH3(CH2),C1, 109-CHCOMe, 78-94-4; CH2=C(Me)CN, 126-98-7; CH,=C(Me)COOEt, 97-63-2; CH2=C(COOEt)CH2COOEt, 2409-52-1 ; cis-CH(COOEt)= CH(COOEt), 141-05-9; CuC1, 7758-89-6; CuBr, 7787-70-4; (n-Bu),P, 998-40-3; CH3(CH,),

Fe(iv) alkylidenes via protonation of Fe(ii) vinyl chelates and a comparative Mössbauer spectroscopic study

“…Prior to this study, [Cp*(dppe)Fe CH(Me)]PF 6 was the only non-aryl Fe( iv ) alkylidene that had undergone X-ray diffraction structural analysis, although numerous related [CpLL′Fe CHR] + complexes have been synthesized. 7 – 9 , 14 – 16 …”

“…Several Fe( iv ) alkylidenes have been synthesized, with two routes utilized in the cases of those structurally characterized ( Fig. 1 ): (1) conversion of [CpLL′Fe C(OR)R′] + via hydride or alkyl anion reagents, 7 – 9 and (2) the addition of diazoalkanes, typically Ph 2 CN 2 , to coordinatively unsaturated complexes or labile precursors. 10 – 13 The subsequent chemistry has been limited to carbene transfers, and some transformations that hint at radical reactions.…”

The Stereospecific Ligand Exchange at a Pseudo‐Benzylic T‐4 Iridium Centre in Planar‐Chiral Cycloiridium (η6‐Arene)tricarbonylchromium Complexes

“…[1][2][3][4][5][6][7][8] Of all the transformations that may take place in the coordination sphere of a metal, ligand exchange [9] at metal centres plays a crucial role and the capability of a given complex to undergo ligand departure and sustain coordinative unsaturation determines the stereochemical outcome of the process (Scheme 1). By virtue of the higher lability of coordinatively unsaturated transition-metal complexes, the ligand retinue is subject to positional rearrangements and to scrambling.…”

New chemical and stereochemical applications of organoiron complexes

“…Transfer of the carbene ligand from optically active transition-metal-carbene complexes to alkenes represents a potentially useful and general method for the enantioselective synthesis of cyclopropanes [ 224 ], and this task was successfully accomplished by the Brookhart group [ 225 ]. The starting complexes were obtained as a pair of iron acyl diastereoisomers, e.g., 58 (2SS) and 59 (2RS), differing in configuration at iron.…”