AcceptorlessDehydrogenationofPrimaryandSecondary AlcoholsCatalysedbyPhosphine-freeC,CChelatedIr(III) NHCComplexes

Herein, an efficient, atom-economic, environmentally benign
catalyticprotocolhasbeendevelopedforsynthesisingketones
and aldehydes by acceptorless dehydrogenationof alcohols.
Theprotocol employsC, Cchelated Ir (III)NHCcomplexes to
promoteacceptorlessdehydrogenationofbothsecondaryand
primaryalcohols. Notably, oxidationof primaryalcohol selec
tivelyyields thecorrespondingaldehydewhere formingester
byproducts is possible. Using C, C chelated Ir (III) NHC
complexes (0.1mol%), andacatalyticamountofbase tBuONa
(5mol%), severalaliphaticandaromaticaldehydesandketones
including more challenging carbonyl compounds bearing heterocyclic ringswereobtained inmoderate tohighyields.
Moreover, the protocol is also efficient for synthesising
industrially important molecules like heliotropin and 3,4,5
trimethoxyacetophenone inmoderateyields. Remarkably, the
catalytic systemallows the straightforward synthesis of the
potentially bio-active compound cholest-4-en-3-one through
acceptorless dehydrogenation followedby doublebond iso
merisationunder thereactionconditions. Lowcatalyst loading,
mild reactionconditions, highselectivity, short reaction time,
andbroad-substratescopesareafewinterestingcharacteristics
ofthecatalyticprotocoldescribedherein.