intermediacy of this compound was confirmed by the reaction of the isolated
3-pyrroline intermediate in the presence of [IrCl(cod)] 2 and acetic acid in refluxing
toluene for 3 h, which furnished the desired pyrrole in 76% yield. Although this step
did not necessarily require a hydrogen acceptor, the added N-phenylmaleimide
significantly accelerated the reaction and was converted into N-phenylsuccinimide.
Li et al. reported the dehydrogenative synthesis of quinazolinones from oaminobenzamides and aldehydes catalyzed by a water-soluble Ir complex in aqueous
media [78]. Specifically, the dehydrative condensation of o-aminobenzamide with
aldehydes was carried out in refluxing water for 2 h to afford 2,3-dihydroquinazolin4(1H )-ones, which was followed by the addition of [Cp*Ir(OH 2 ) 3 ][OTf] 2 (43)
(1 mol%) and further reflux for 1 h to afford quinazolinones in good yields (Scheme
29). The dehydrogenation of isolated 2,3-dihydroquinazolin-4(1H )-one in refluxing
water was confirmed to yield quinazolinones almost as equal efficiently as the
one-pot process.
Scheme 28 Intermediacy of 3-pyrroline and following dehydrogenation
Scheme 29 Dehydrogenative synthesis of quinazolinones from o-aminobenzamide and aldehydes
Iridium-Catalyzed Dehydrogenative Reactions
23
3-pyrroline intermediate in the presence of [IrCl(cod)] 2 and acetic acid in refluxing
toluene for 3 h, which furnished the desired pyrrole in 76% yield. Although this step
did not necessarily require a hydrogen acceptor, the added N-phenylmaleimide
significantly accelerated the reaction and was converted into N-phenylsuccinimide.
Li et al. reported the dehydrogenative synthesis of quinazolinones from oaminobenzamides and aldehydes catalyzed by a water-soluble Ir complex in aqueous
media [78]. Specifically, the dehydrative condensation of o-aminobenzamide with
aldehydes was carried out in refluxing water for 2 h to afford 2,3-dihydroquinazolin4(1H )-ones, which was followed by the addition of [Cp*Ir(OH 2 ) 3 ][OTf] 2 (43)
(1 mol%) and further reflux for 1 h to afford quinazolinones in good yields (Scheme
29). The dehydrogenation of isolated 2,3-dihydroquinazolin-4(1H )-one in refluxing
water was confirmed to yield quinazolinones almost as equal efficiently as the
one-pot process.
Scheme 28 Intermediacy of 3-pyrroline and following dehydrogenation
Scheme 29 Dehydrogenative synthesis of quinazolinones from o-aminobenzamide and aldehydes
Iridium-Catalyzed Dehydrogenative Reactions
23