Syntheses, Structures, Reactivity, and Catalytic Applications of Enantiopure Rhenium-Containing P-Stereogenic Phosphonium Salts, Phosphines, Phosphine Boranes, and Phosphine Oxides
Castillo Molina DA, Seidel FO, Pathak K, Williams SA, Hampel F, Gladysz JA (2025)
Publication Type: Journal article
Publication year: 2025
Journal
Book Volume: 44
Pages Range: 1688-1704
Journal Issue: 15
DOI: 10.1021/acs.organomet.5c00171
Abstract
Easily accessed enantiopure (η5-C5H5)Re(NO)(PPh3)(CH3) is treated with Ph3C+PF6–(−78 °C) to generate the methylidene cation [(η5-C5H5)Re(NO)(PPh3)(=CH2)]+and then racemic chiral secondary phosphines PHXX′ (4; X/X′ = a, tBu/Ph; b, Cy/Ph; c, tBu/Cy; d, CH3/Ph; e, 2-furyl/Ph; f, α-naph/Ph; g, β-naph/Ph) to give the phosphonium salts (SReRP)- and (SReSP)-[(η5-C5H5)Re(NO)(PPh3)(CH2PHXX’)]+PF6–(2·H+) as mixtures of Re, P-diastereomers that are usually separable (a,b,c,f,g). Treatment of 2a-g·H+with tBuOK generates the phosphines 2a-g, which are variously isolated (2f,g), treated with BH3·S(CH3)2to give 2a-e·BH3, or oxidized (O2or PhIO) to give 2a-c·O. Oxidations are also effected with 2a,c that has been generated from 2a,c·BH3and pyrrolidine. For the diastereomerically pure complexes in the a-c series, configurations have been assigned crystallographically, and the Ph3P–Re–CH2–P−X conformations were analyzed in detail. In an unusual but precedented phenomenon, the diastereomers of 2a·H+PF6–cocrystallize. 2f,g catalyze highly enantioselective intramolecular Morita–Baylis–Hillman cyclizations of R(CO)CH═CHCH2CH2CHO (R═Ph, SiPr), and (SReSP)-2b (2.4 mol %) and [Pd(allyl)Cl]2(1.2 mol % based upon “Pd atoms”) give a catalyst for the allylic alkylation of racemic 3-(acetoxy)cyclohexene that furthermore effects a kinetic resolution of the educt (s = 15.0).
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APA:
Castillo Molina, D.A., Seidel, F.O., Pathak, K., Williams, S.A., Hampel, F., & Gladysz, J.A. (2025). Syntheses, Structures, Reactivity, and Catalytic Applications of Enantiopure Rhenium-Containing P-Stereogenic Phosphonium Salts, Phosphines, Phosphine Boranes, and Phosphine Oxides. Organometallics, 44(15), 1688-1704. https://doi.org/10.1021/acs.organomet.5c00171
MLA:
Castillo Molina, Dante A., et al. "Syntheses, Structures, Reactivity, and Catalytic Applications of Enantiopure Rhenium-Containing P-Stereogenic Phosphonium Salts, Phosphines, Phosphine Boranes, and Phosphine Oxides." Organometallics 44.15 (2025): 1688-1704.
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