Impact on Hydrogenation Catalytic Cycle of the R Groups’ Cyclic Feature in “R-SMS-Phos”

Abstract

A series of R-SMS-Phos ligands was evaluated in the Rh(I)-catalyzed hydrogenation of a set of olefins showing a marked influence of the cyclic nature and structure of the R groups. Overall, cPen- and Cy-SMS-Phos performed efficiently, while Ph- and Bn-SMS-Phos exhibited slower kinetics and furnished lower ee's also compared with C(6)F(5)CH(2)-SMS-Phos. The Rh(I)-(Cy-SMS-Phos) catalyst was screened under mild conditions displaying excellent enantioselectivities and high TOFs. Cases of catalysis under catalyst or substrate control were identified.

Stereoselective Synthesis of P-Stereogenic Aminophosphines: Ring Opening of Bulky Oxazaphospholidines

“…For stereoselective synthesis of P*-compounds, the main alternative to enantioselective deprotonation is ring opening of oxazaphospholidines (Scheme ). The pioneering work of Jugé − showed that both the condensation of a bis(dialkylamino) phenylphosphine with (−)-ephedrine and the ring opening of the resulting oxazaphospholidine ( I ) with alkyllithium reagents to give II are highly diastereoselective . This elegant work has been used to prepare several P-stereogenic ligands .…”

“…The pioneering work of Jugé − showed that both the condensation of a bis(dialkylamino) phenylphosphine with (−)-ephedrine and the ring opening of the resulting oxazaphospholidine ( I ) with alkyllithium reagents to give II are highly diastereoselective . This elegant work has been used to prepare several P-stereogenic ligands . However, it is not amenable to the synthesis of bulky P*-building blocks, due to the lack of reactivity of intermediate II when a bulky group is attached to the phosphorus …”

Rh/SPO-WudaPhos-Catalyzed Asymmetric Hydrogenation of α-Substituted Ethenylphosphonic Acids via Noncovalent Ion-Pair Interaction

“…Catalytic asymmetric hydrogenation of α-substituted ethenylphosphonic acids was regarded as one of the most straightforward and efficient methods to access chiral α-substituted ethylphosphonic acids. However, little research work involved the asymmetric hydrogenation of α,β-unsaturated phosphonic acids . In 2001, Genet et al reported Ru-catalyzed asymmetric hydrogenation of α,β-unsaturated phosphonic acids to prepare optically active 1-arylethylphosphonic acids (Scheme a) .…”

“…However, little research work involved the asymmetric hydrogenation of α,β-unsaturated phosphonic acids. 13 In 2001, Genet et al reported Ru-catalyzed asymmetric hydrogenation of α,β-unsaturated phosphonic acids to prepare optically active 1-arylethylphosphonic acids (Scheme 1a). 14 However, this hydrogenation required vigorous conditions and gave only moderate enantioselectivities.…”

Catalytic asymmetric hydrogenation using a [2.2]paracyclophane based chiral 1,2,3-triazol-5-ylidene–Pd complex under ambient conditions and 1 atmosphere of H2

“…Assignment of absolute conguration of the products is based on correlation of the observed optical rotation with the literature (ESI †). 46,47 Methyl a-acetamidoacrylate was hydrogenated to the corresponding saturated ester with 81% ee and in near quantitative yield.…”