Secondary 1,3,2-diazaphospholenes have a polarized P-H bond and are emerging as molecular hydrides. Herein, a class of chiral, conformationally restricted methoxy-1,3,2-diazaphospholene catalysts is reported. We demonstrate their catalytic potential in asymmetric 1,4-reductions of α,β-unsaturated carbonyl derivatives, including enones, acyl pyrroles, and amides, which proceeded in enantioselectivities of up to 95.5:4.5 e.r.

1,3,2‐Diazaphospholenes (DAPs) are an emerging class of organic hydrides. In this work, we exploited them as efficient catalysts for very mild reductive Claisen rearrangements. The method is tolerant towards a wide variety of functional groups and operates at ambient temperature. Besides being enantiospecific for substrates with existing stereogenic centers, the diastereoselectivity can be switched by varying solvents and DAP catalysts. The reaction kinetics show direct rearrangements of O‐bound phospholene enolates and provide a proof‐of‐principle for catalytic enantioselective reactions.

The potent nucleophilicity and remarkably low basicity of 1,3,2‐diazaphospholenes (DAPs) is exploited in a catalytic, metal‐free 1,4‐reduction of free α,β‐unsaturated carboxylic acids. Notably, the reduction occurs without a prior deprotonation of the carboxylic acid moiety and hence does not consume an additional hydride equivalent. This highlights the excellent nucleophilic character and low basicity of DAP‐hydrides. Functional groups such as Cbz group or alkyl halides which can be problematic with classical transition‐metal catalysts are well tolerated in the DAP‐catalyzed process. Moreover, the transformation is characterized by a low catalyst loading, mild reaction conditions at ambient temperature as well as fast reaction times and high yields. The proof‐of‐principle for a catalytic enantioselective version is described.

Indoleamine-2,3-dioxygenase-1 (IDO1) is a critical immunoregulatory enzyme responsible for the metabolism of tryptophan during inflammation and disease. Based upon a pyranonaphthoquinone framework, the first examples of indoleamine-2,3-dioxygenase-1 (IDO1) inhibitors containing a carborane cage are reported. The novel closo-1,2-carboranyl-N-pyranonaphthoquinone derivatives display low μM binding affinity for the human recombinant enzyme, with IC50 values ranging from 0.78 to 1.77 μM.

Secondary 1,3,2-diazaphospholenes have apolarized P À Hb ond and are emerging as molecular hydrides.H erein, ac lass of chiral, conformationally restricted methoxy-1,3,2diazaphospholene catalysts is reported. We demonstrate their catalytic potential in asymmetric 1,4-reductions of a,b-unsaturated carbonyl derivatives,including enones,acyl pyrroles,and amides,w hichp roceeded in enantioselectivities of up to 95.5:4.5 e.r.