Сhiral tricyclic phosphines derived from 1-(+)-neomenthyl-1,2-diphosphole: Synthesis and applications in asymmetric homogeneous catalysis

- The first example of using a chiral phosphine with a PP bond in asymmetric catalysis.
- 2 Chiral diphosphines were prepared from 1-(+)-neomenthyl-1,2-diphosphole.
- The phosphines were utilized in Pd-catalyzed allylic substitution (ee = 25%).
- [3 + 2] Organocatalytic cyclization of allenes with alkenes gave up to 68% ee.

A one-step diastereoselective synthesis of bulky P-chiral phosphines with a rigid bicyclic [2.2.1] structure was developed employing a cycloaddition reaction of 3,4,5-triphenyl-1-(+)-neomenthyl-1,2-diphosphole (1) and maleic acid derivatives. The catalytic activity and asymmetric induction for the prepared enantiopure tricyclic phosphines 2a and 3a were evaluated in Pd-catalyzed asymmetric allylic substitution and [3 + 2] organocatalytic cyclization of allenes with activated alkenes (ee = 68%). This is the first example of using a chiral phosphine with a PP bond as ligand in allylic alkylation and organocatalyst in a [3 + 2] annulation.

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