(S)-5,5'-Bis(diphenylphosphino)-4,4'-bi-1,3-benzodioxole

Preparation

Add phosphine oxide (50 mg) to a flame-dried Schlenk flask. Empty the flask and backfill with N2. Add THF (1 mL), PMHS (120 mg, 2.0 mmol, 25 equivalents based on "SiH"), and Ti(OiPr)4 (50 mg, 0.176 mmol, 2.2 equivalents) sequentially to the mixture using a syringe. Stir the resulting mixture at 70°C for 24 hours. Cool the reaction mixture to room temperature. Pass the reaction mixture through a silica gel pad containing EtOAc. Add NaOH aqueous solution (5 mL, 1 M) and KF aqueous solution (5 mL, saturated) to the mixture to quench the reaction. Stir the mixture at room temperature for 1 hour. Extract the reaction mixture with EtOAc. Dry the reaction mixture with MgSO4. Concentrate the reaction mixture. Purify the crude product by rapid silica gel chromatography to give the title compound (S)-5,5'-Bis(diphenylphosphino)-4,4'-bi-1,3-benzodioxole.

Reaction

1. Biaryl bisphosphine ligand with narrow dihedral angle. The SEGPHOS® ligand has been applied to a variety of metal catalyzed reactions. In many cases, yields and enantioselectivities, exceed results obtained earlier using BINAP.
2. As ruthenium complex, SEGPHOS® generally gives higher levels of chiral induction in asymmetric hydrogenations of α,β,and γ-functionalized ketones. See ruthenium complexes 44-0096, 44-0518, 44-0168.
3. Used in Rh-catalyzed transformations such as: (a) 1,4-addition of boronic acids to coumarins,4 (b) addition of titanium reagents to imines, (c) cotrimerization of alkenes and acetylenes, (d) double [2+2+2] cycloaddition,11 (e) indanone formation.12a,b
4. Used in Pd-catalyzed transformations such as: (a) cycloaddition of 1,6-enyne, (b) arylative cyclization of allenyl aldehydes with boronic acids,13 (c) synthesis of chromans.
5. Used in Cu-catalyzed transformations such as: (a) nitroso Diels-Alder, (b) reductive aldol condensation, (c) conjugate reduction of unsaturated sulfones,15 and phophonates.
6. Iridium-catalyzed asymmetric hydrogenation of quinolines activated by chloroformates. 

Chemical Properties

(S)-(-)-5,5'-bis(diphenylphosphine)-4,4'-di-1,3-benzodioxide has certain stability and rigidity, and can undergo reduction and coupling reactions.

Uses

(S)-(-)-SEGPHOS is a chelating ligand used to prepare coordination complex catalysts, such as its use in Pd catalysts for the enantioselective synthesis of spiro- or benzofused hetereocycles with exocyclic olefins via enantioselective intramolecular dearomative Heck reaction of indoles, benzofurans, pyrroles and furans.