A Novel Synthesis of 1‐Alkyl‐2‐phenyl‐(2,3‐dihydro‐)1,8‐naphthyridin‐4‐ones from 2‐Chloronicotinic Acid

Park

2021

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N-Methoxy-N-methylamides were prepared by the acylation of acid halides, acyl cyanides, esters, lactones, activated amides, and mesyl carboxylates with N,O-dimethylhydroxylamine hydrochloride. The reaction of carboxylic acids with alkyl chloroformates, phosphonate reagents, or coupling agents afforded the activated esters, which were converted to N-methoxy-N-methylamides by (CH 3 O)NHCH 3 . N-Methoxy-N-methylamides were also prepared by the oxidative amidation of benzyl alcohols and palladiumcatalyzed aminocarbonylation of organoboronic acids or aryl halides with (CH 3 O)NHCH 3 under CO equivalents. Furthermore, N-methoxy-N-methylamides were produced by the selective substitution of N,O-dimethylcarbamoylation agents with organometallic reagents.

Section: Preparation Via (Mixed) Carboxylic Anhydridesmentioning

confidence: 99%

Synthetic Approaches to N‐Methoxy‐N‐methylamides

Park

2021

Self Cite

A review of the syntheses of (thio)flavones, 4‐quinolones, (thio)aurones, and azaaurones from 2′‐substituted alkynones

2021

Flavones have been prepared by the 6-endo cyclization of o-alkynoylphenols, cyclization/deprotection of 2 0 -protected alkynones, or carbonylative coupling of 2-halophenols with arylacetylenes and subsequent cyclization. (Z)-Aurones have been prepared by the 5-exo cyclization of o-alkynoylphenols or oxidation of (Z)-benzylidenebenzofuran-3-ols with MnO 2 . Thioflavones have been prepared by deprotection/6-endo cyclization of S-protected alkynones or by the addition of sulfur to 2 0 -halo(methoxy)alkynones and subsequent cyclization. Deprotection and 5-exo cyclization of S-benzylated alkynones using HCOOH afforded (Z)-thioaurones. 2-Phenyl-4-quinolones have been prepared by the 6-endo cyclization of 2 0 -aminoalkynones or by the addition of amines to 2 0haloalkynones and subsequent cyclization. Furthermore, the treatment of 2 0aminoalkynones with triphenylphosphine afforded (Z)-azaaurones by 5-exo cyclization.

A review of the syntheses of flavanones, thioflavanones, and azaflavanones from 2'‐substituted chalcones

2021

Flavanones have been prepared by the cyclization of 2'-hydroxychalcones using acidic reagents, such as H 2 SO 4 , HX, CF 3 COOH, CH 3 SO 3 H, KF-celite, or SiO 2 . Treatment of 2'-hydroxychalcones with bases, such as LiOH, KOH, NaOAc, K 2 CO 3 , pyridine, Et 3 N, or N-methylimidazole afforded flavanones. The conversion of 2'-hydroxychalcones to flavanones has been conducted using Co(salpr), K 3 Fe (CN) 6 , CuO, or Ni(Tfacac) 2 . Thioflavanones have been prepared by deprotecting and cyclizing S-protected chalcones using AgNO 3 , HBr, CF 3 COOH, or NaOH and by adding NaSH or KCS 2 OEt to 2'-halochalcones and subsequent substitution. Azaflavanones have been prepared by cyclizing 2'-aminochalcones using acidic reagents, such as H 3 PO 4 , HCl, silica chloride, or K-10 clay. Furthermore, treatment of 2'-aminochalcones with Lewis acids, such as ZnCl 2 , SbCl 3 , Yb(OTf) 3 , InCl 3 , TaBr 5 , or CeCl 3 afforded azaflavanones, and chiral azaflavanones were prepared by cyclizing 2'-aminochalcones in the presence of per-6-ABCD, chiral amine, BINOL-phosphoric acid, or thiourea catalyst.