Acyl cyanides as carbonyl heterodienophiles: application to the synthesis of naphthols, isoquinolones, and isocoumarins

Abstract

Irradiation of 2-methylbenzoyl cyanide (3a) in acetonitrile solution results in the formation of its dimer, which upon loss of HCN gives rise to the cycloadduct 7a. The dimerization also proceeds efficiently with derivatives of 3a giving adducts 7b and 7c. When 2-methylaroyl cyanides are photolyzed in the presence of a more reactive acyl cyanide the mixed adducts 8a-e are obtained in excellent yields. The cycloadducts 70-c and 80-e react with carbon and nitrogen nucleophiles by a tandem addition-cyclization sequence furnishing substituted naphthols (IOU and lob) and isoquinolones (lla-d), respectively. Isocoumarins 12a and 12b were prepared from the adducts 8a and 8e by treatment with potassium tert-butoxide in THF.Key words: naphthols, isoquinolones, isocoumarins, synthesis of; acyl cyanides; hetero Diels-Alder.Resume : L'irradiation du cyanure de 2-mtthylbenzoyle (3a) en solution dans l'acttonitrile conduit 5 la formation de son dimkre qui, par perte de HCN, fournit le cycloadduit 7a. La dimerisation se produit aussi d'une faqon efficace avec les dtrivts du compost 30; elle conduit alors aux composts 70 et 7c. Lorsqu'on effectue la photolyse des cyanures de 2-mtthylaroyle en prtsence d'un cyanure d'acyle plus rtactif, on obtient alors les produits mixtes 8u-e avec d'excellents rendements. Les cycloadduits 7u-c et 8a-e rtagissent avec les nucltophiles carbones et azotts par une sequence de rtactions d'additioncyclisation en tandem qui fournissent respectivement des naphtols (10a et lob) et des isoquinoltines (lla-d) substituts. Par reaction des adduits 8a et 8e avec du ferf-butylate de potassium dans le THF, on a prepart les isocoumarines 120 et 120.

Substituted Naphthols: Preparations, Applications, and Reactions

“…There currently exists a number of methods for synthesizing varied naphthol derivatives. [ 25–28 ] Different chemical strategies have been employed for the synthesis of the naphthol skeleton, such as, C–H activation catalyzed by transition‐metals, [ 29 ] cyclizations, [ 30 ] Diels‐Alder reactions, [ 31 ] Claisen rearrangements, [ 32 ] pyrolysis reactions, [ 33 ] and chemical reductions, [ 34 ] amongst others. [ 35–38 ]…”

Efficient synthesis of some 3-substuited-1(2H)-isoquinolones

“…The latter method has been used in the synthesis of (±)-licoricidine [22], narciclasine [23], (+)-deoxypancratistatin [24], and the benzophenanthridine alkaloid nitidine [25]. In addition, the [4+2]-cycloaddition of the ketenes to cyano ketones [26], treatment of indanones with sodium azide [27], the recently reported solid-phase synthesis of isoquinolinones using Bischler-Napieralski cyclization [28], the palladium-mediated synthesis of isoquinolinones [29], and syntheses via Curtius arrangement of cinnamic acids or via an isoquinolone N-oxide have been reported [30].…”

Efficient synthesis of some 3-arylisoquinolin-1(2H)-ones

“…The latter method has been used in the synthesis of (±)-licoricidine [23], narciclasine [24], (+)-deoxypancretistatin [25], and the benzophenanthridine alkaloid nitidine [26]. In addition, the [4+2] cycloaddition of the ketenes to cyano ketones [27], treatment of indanones with sodium azide [28], recently reported solid-phase synthesis of isoquinolinones using Bischler-Napieralski cyclization [29], palladium-mediated synthesis of isoquinolinones [30], and syntheses via Curtius arrangement of cinnamic acids or via an isoquinolone N-oxide have been reported [31].The substitution of the oxygen by nitrogen atom is still one of the most important methods. A number of reagents have been used including ammonia, ammonium acetate, or amines, but the results are never satisfactory [32-34] except for a recently reported method [35].…”