Ligand maps lead to treasure! The activity of complexes of fluorophosphines (R2PF) in catalytic hydroformylation and hydrocyanation is predicted from a ligand map. However, the instability of R2PF to disproportionation is well‐documented. Examples of R2PF ligands (see scheme) are described that are stabilized to such an extent that they can be used in catalysis and are shown to be highly effective.

The preparation of a range of asymmetric iron and ruthenium-cyclone complexes, and their application to the asymmetric reduction of a ketone, are described. The enantioselectivity of of ketones reduction is influenced by a single chiral centre in the catalyst, as well as by the planar chirality in the catalyst. This represents the first example of asymmetric ketone reduction using an iron cyclone catalyst. Introduction 10The ruthenium complex 1 (the Shvo catalyst)1-4 reversibly splits to give hydride 2 and the unsaturated species 3.15 By 'shuttling' between 2 and 3, the Shvo catalyst transfers pairs of hydrogen atoms between secondary alcohols and ketones and has been used to good effect in dynamic kinetic resolution (DKR) reactions of alcohols and amines.2,3 There is evidence, 4 largely based on kinetic isotope effects, that the 20 hydrogen transfer to ketones and aldehydes, by the Shvo catlyst, takes place via a concerted 'outer sphere' mechanism ( Figure 1a). This is analogous to that of of ketone reduction by the Noyori catalyst 4 (Figure 1b). The Shvo catalyst is also an efficient ketone reducing agent when using an excess of an alcohol (usually iPrOH) or formic acid as hydrogen source, 1d and can also catalyse hydrogenation reactions. 1b,c,4d,6 The closely related iron complex 5 has recently been prepared from the tricarbonyl 35 precursor 6 7 and employed in catalytic reduction reactions of ketones by Casey and Guan.8 The mechanism appears to be analogous to that of the Shvo catalyst 2 (Figure 1c). In recent studies, complex 5 has been applied to the oxidation of alcohols using acetone as an acceptor, and a number of its 40 derivatives have been reported and evaluated in this role. 9 In our own studies, 10 we reported the synthesis and applications of racemic complexes 7a-7g in alcohol oxidations. The complexes were formed by an intramolecular cyclisation from a linear dialkyne precursor 8, followed by diastereoisomer 45 separation. 7,1150

The secondary phosphine CgPH (CgP = 6-phospha-2,4,8-trioxa-1,3,5,7-tetramethyladamantyl group) is made in 50% yield by a modification of the literature method (avoiding high pressures of PH3) by bubbling PH3 through an acidified solution of 2,4-pentanedione at 0 °C. Under similar conditions the ethyl analogue EtCgPH is formed from 3,5-heptanedione in 75% yield. The halophosphines CgPCl and CgPBr are made by treatment of CgPH with N-halosuccinimide. CgPBr is also made by treatment of CgPH with Br2. Three methods are described for the synthesis of CgPR, where R = alkyl: (a) the previously reported acid-catalyzed condensation reaction of RPH2 with 2,4-pentanedione, which has been extended to R = iPr; (b) treatment of CgP(BH3)Li with RX followed by borane deprotection with Et2NH, which has been used for R = iPr, benzyl, n-C20H41; (c) treatment of CgPBr with RMgX, which has been used for R = iPr, Me. The complexes [PtCl2(CgPH)2] (1), [PdCl2(CgPH)2] (2), [PdCl2(CgPR)2] (where R = iPr (3a), Cy (3b)), and [PtCl2(CgPR)2] (where R = iPr (4a), Cy (4b), n-C20H41 (4c)) are described. The crystal structures of CgPH, CgPCl, [CgP(CH2Ph)2]Br, CgP(n-C20H41), and complexes 1, 3b, and 4c are reported. From the ν(CO) values for trans-[RhCl(CO)(CgPX)2], the σ-donor/π-acceptor properties of CgPX are in the order X = iPr > Me > Ph > H > Cl.

An efficient, classical resolution of the versatile P-ligand intermediate 6-phospha-2,4,8-trioxa-adamantane (CgPH) is described and the rhodium complex of the optically pure secondary phosphine beta-CgPH is an active and moderately selective asymmetric hydrogenation catalyst.