Bicyclic hydrazine, asymmetric

Formal hydration of the double bond appeared by the hydroboration-oxidation sequence. Desymmetrization reactions with catalytic asymmetric hydroboration are not restricted to norbornene or nonfunctionalized substrates and can be successfully applied to meso bicyclic hydrazines. In the case of 157, hydroxy derivative 158 is formed with only moderate enantioselectivity both using Rh or Ir precatalysts. Interestingly, a reversal of enantioselectivity is observed for the catalytic desymmetrization reaction by exchanging these two transition metals. Rh-catalyzed hydroboration involves a metal-H insertion, and a boryl migration is involved when using an Ir precatalyst (Equation 17) <2002JA12098, 2002JOC3522>. 

The catalytic asymmetric hydroboration reaction can also be applied to OTei o-bicyclic hydrazines. The resulting alcohols are of great synthetic interest and can lead to cyclopentanic diamino alcohols with good enantiomeric purity (equation 14). Interestingly, a reversal of enantioselectivity is observed between reactions employing rhodium and iridium catalysts. ... 

Bexrud and Tautens used chiral NFlC-based bis-carbonyl compound 54 in the asymmetric hydroarylation of bicyclic Ai-Boc protected hydrazines with arylbor-onic acids (Scheme 10.3), and observed good yields (up to 86%) and excellent ee values (up to 93%) [32]. Noteworthy, no p-nitrogen-catalyzed ring-opening of the diazabicycles was observed. 

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