Abstract
The enantioselective organocatalytic reduction of aryl-substituted nitroenamines was
successfully performed under continuous-flow conditions. After a preliminary screening
with a 10-μL microreactor, to establish the best reaction conditions, the reduction
was scaled up in a 0.5-mL mesoreactor, without appreciable loss of enantioselectivity,
that remained constantly higher than 90%. The in-flow nitro reduction was also accomplished,
either by Raney nickel catalyzed hydrogenation or by a metal-free methodology based
on the use of the very inexpensive and readily available reducing agent trichlorosilane.
The final aim is to develop a two-step, continuous-flow process for the stereoselective,
metal-free, catalytic synthesis of differently functionalized chiral 1,2-diamines.
Key words
flow chemistry - chiral diamines - microreactors - nitroenamines - organocatalysis
