Reductive Cleavage of an N-O Bond

During the development of carbapenem (+)-PS-5 as an antibiotic agent, Naito et 

In addition to being more selective, dissolved calcium metal functions in a similar way to lithium and sodium metals towards organic functional groups [45]. Tab. 4.2 lists reductions giving the same products by the three dissolved metals. Among these, calcium affords the highest yields for some substrates (entries 1-3). The compounds in Tab. 4.2 include an aldehyde, indole [46], aryl ketone, enone, naphthalene [47], pyridine N-oxide [48], benzyl alcohol, styrene, and buckminster-fullerene. 

---

The domino process is triggered by reductive cleavage of an N-O bond in nitronate 84 using Adams catalyst to give 86 containing a reactive aldehyde and amine functionality via 85. Compound 86 then leads to cyclic imine 87, which under the reaction conditions is hydrogenated to give cyclic amine 88. The final step of the domino process is a cyclization to afiford 89 (Scheme 9.17) [37]. 

---