Subtleties in asymmetric catalyst structure: the resolution of a 6-phospha-2,4,8-trioxa-adamantane and its applications in asymmetric hydrogenation catalysis

Abstract

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.

Silver‐Catalysed Enantioselective Addition of OH and NH Bonds to Allenes: A New Model for Stereoselectivity Based on Noncovalent Interactions

“…Silver(I) complexes 1‐Ag and 2‐Ag were prepared from the reactions of Ag 2 CO 3 with β‐CgPOOH ( 1‐H )8, 9 and TADDOL‐POOH ( 2‐H ),10 respectively. These complexes, which were isolated as white solids and were soluble in most organic solvents, were fully characterised.…”

“…For the formation of both compounds 4 a and 7 c , two diastereomeric transition states were located that corresponded to both the R and S enantiomers in the presence of the chiral anion ( 1R,3S,5S,7R )‐tetramethyl‐2,4,6‐trioxa‐8‐phosphatricyclo[3.3.1.13.7]decan‐8‐ol‐8‐oxide8 (for transition‐state 3D model coordinates and animations of the normal reaction modes, see Web Table 2). The calculated discrimination for compound 4 a (0.2 kcal mol −1 ) favours the assignment ( R )‐ 4 a , but such a small magnitude merely confirms that the reaction proceeds with a low ee value.…”

“…Synthesis of 1‐Ag (method 1) : Ag 2 CO 3 (0.5 equiv) was added in a single portion to a solution of 1‐H 8, 25 (1 equiv) in EtOH (5 mL). The resulting mixture was protected from light and stirred vigorously overnight.…”

Is restricted M–P rotation a common feature of enantioselective monophos catalysts? An example of restricted Rh–P rotation in a secondary phosphine complex

“…11 The a-CgPH has now been separated and was used throughout this study. The absolute stereochemistry in a-CgPOOH and a-CgPH has been confirmed by X-ray crystallography.…”

Metal(II) template assisted syntheses of two P―C―O―P chelating ligands incorporating a bulky 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phosphaadamantyl cage

“…Further studies are currently in progress to probe the variability of this reaction and to explore the coordination chemistry and stability of these new M-P-C-O-P metallacycles. Recent studies have shown that metal complexes of phosphines incorporating the 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phosphaadamantyl cage have found important catalytic uses [25].…”