| CPC C07D 487/14 (2013.01) [C07B 2200/05 (2013.01)] | 6 Claims |

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1. A compound of general formula I
![]() wherein residues X1a, X1b, X2a, and X2b each are deuterium and residues X3a, X3b, X4a, X4b, X5a, and X5b each are hydrogen.
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