Ceric ammonium nitrate , Mannich reaction

A Mannich-type reaction is used in the PictetSpengler synthesis of tetrahydroisoquinolines 181 (Scheme 108) . Indoles similarly give -carbolines (Section 3.3.1.5.7.4). A variation of the PictetSpengler reaction involves the oxidative cyclization of 182 using ceric ammonium nitrate (CAN) (Scheme 109) <1998JOC860>. 

Decreased reaction times have also been reported with the use of ceric ammonium nitrate (CAN). In the reaction of acetophenone 58, aldehyde 59, and amine 60 to afford Mannich base 61, the reaction time was reduced from 42 h to 7 h and the yield improved from 30 to 98% in going from no CAN to 5 mol %. 

Diverse dihydronaphtho[l,2-(r]furans were generated fix)m 1,4-naphthoquinones and olefins in the presence of ceric ammonium nitrate (13OBC6097). ( )-Lantalucratins A and B were produced in the presence of diammonium cerium(IV) nitrate (13T10470).Benzo[(>]furan moieties were synthesized by a three-component Mannich reaction of 3-acetyl-2H-chromen-2-one or l-(l-benzo[fc]fioran-2-yl) ethanone with p-substituted aromatic aldehydes and aromatic amines with ceric ammonium nitrate (CAN) as a catalyst (13MCR4787).p-Alkenylphenols went through the oxidative dimerization to generate substituted dihydrobenzo[l)]furans in the presence of CAN (13T653). 

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