New axially chiral atropos and tropos secondary diamines as ligands for enantioselective intramolecular hydroamination

The highly constrained, axially chiral atropos diamines (Ri,S,S)-1, (Ri,R,R)-1 and (Ri,S,R)-1 and their tropos analogue (Ri)-2 have been prepared via bis-N,N-dialkylation of (R)-2,2′-diamino-1,1′-binaphthyl, using either (R)- or (S)-2,2′-bis(bromomethyl)-1,1′-binaphthyl and 2,2′-bis(bromomethyl)-1,1′-biphenyl as alkylating agents, followed by selective nickel chloride-catalysed bis(mono-hydrogenolysis) of the tertiary amino groups of the so-obtained (Ri,R,R)-4, (Ri,S,S)-4, (Ri,R,S)-4 and (Ri)-6, respectively, by lithium aluminium hydride in refluxing THF or THF/diglyme. The diamines (Ri,S,S)-1, (Ri,R,R)-1, (Ri,S,R)-1 and (Ri)-2 have been evaluated as ligands for ytterbium-catalysed intramolecular hydroamination and compared to the ligand 1,1′-binaphthyl-2,2′-bis(benzylamine) (Ri)-3. They afforded highly active catalysts for the cyclisation of aminopentenes and aminohexenes with up to 58% ee.

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C64H44N2[α]43625=-238 (c 0.2, CHCl3)Absolute configuration: (R,R,R) (assigned by comparison)

C64H44N2[α]43625=-4256 (c 0.23, CHCl3)Absolute configuration: (R,S,S) (assigned by comparison)

C64H44N2[α]43625=-2070 (c 0.2, CHCl3)Absolute configuration: (R,R,S) (assigned by comparison)

C48H36N2[α]43625=-1096 (c 0.5, CH2Cl2)Absolute configuration: (R) (assigned from (R)-2,2′-diamino-1,1′-binaphthyl)

C42H30N2[α]43625=+1970 (c 0.2, CHCl3)Absolute configuration: (R,R) (assigned by comparison)

C42H30N2[α]43625=-1779 (c 0.2, CHCl3)Absolute configuration: (R,S) (assigned by comparison)

C64H48N2[α]43625=-177 (c 0.2, CHCl3)Absolute configuration: (R,S,S) (assigned by comparison)

C64H48N2[α]43625=-124 (c 0.2, CHCl3)Absolute configuration: (R,R,R) (assigned by comparison)

C64H48N2[α]43625=-128 (c 0.2, CHCl3)Absolute configuration: (R,S,R) (assigned by comparison)

C48H40N2[α]43625=+81 (c 0.5, CH2Cl2)Absolute configuration: (R) (assigned from (R)-2,2′-diamino-1,1′-binaphthyl)

C34H28N2[α]43625=+353 (c 1.4, CHCl3)Absolute configuration: (R) (assigned from (R)-2,2′-diamino-1,1′-binaphthyl)