Synthesis of Highly Substituted Aniline and o-Phenylenediamine Derivatives Containing Various Substitution Patterns

Flow synthesis of coumalic acid and its derivatization

Coumalic acid is a valuable platform compound which can be prepared from malic acid, a biorenewable feedstock derived from glucose. Two flow syntheses of coumalic acid and a new heated rotating reactor are presented.

Regioselective Hydrolysis and Transesterification of Dimethyl 3-Benzamidophthalates Assisted by a Neighboring Amide Group

An efficient, highly regioselective hydrolysis and transesterification of dimethyl 3-benzamidophthalates into the corresponding carboxylic acid monoesters and mixed esters (including tert-butyl esters) under basic conditions is presented. The selectivity is governed by the neighboring 3-benzamido moiety's participation and by the nature of the solvent. In alcohols the reaction occurred exclusively at the ortho-position to the benzamido functionality, in pyridine or acetonitrile at both ester groups. An insight into the mechanistic pathway was obtained from a (1)H NMR study in perdeuteromethanol.

Gold-catalyzed formal [4π + 2π]-cycloadditions of propiolate derivatives with unactivated nitriles

Gold-catalyzed hetero-[4π + 2π]-cycloadditions of tert-butyl propiolates with unactivated nitriles are described. This new finding enables a one-pot gold-catalyzed synthesis of highly substituted pyridines.

Gold-catalyzed hetero-[4π + 2π]-cycloadditions of tert-butyl propiolates with unactivated nitriles are described; the resulting 6H-1,3-oxazin-6-ones are not easily accessible via conventional methods. This new finding enables a one-pot gold-catalyzed synthesis of highly substituted pyridines through sequential gold-catalyzed reactions of tert-butyl propiolates with nitriles, and then with electron-deficient alkynes in the same solvent. The utility of these [4 + 2]-cycloadditions is further expanded with various aldehydes, ketones and 2-phenyloxetane, yielding satisfactory yields of cycloadducts.

Methyl 2-benzamido-4-(3,4-dimethoxyphenyl)-5-methylbenzoate and N-{5-benzoyl-2-[(Z)-2-methoxyethenyl]-4-methylphenyl}benzamide

Methyl 2-benzamido-4-(3,4-dimethoxyphenyl)-5-methylbenzoate, C(24)H(23)NO(5), (Ia), and N-{5-benzoyl-2-[(Z)-2-methoxyethenyl]-4-methylphenyl}benzamide, C(24)H(21)NO(3), (IIa), were formed via a Diels-Alder reaction of appropriately substituted 2H-pyran-2-ones and methyl propiolate or (Z)-1-methoxybut-1-en-3-yne, respectively. Each of these cycloadditions might yield two different regioisomers, but just one was obtained in each case. In (Ia), an intramolecular N-H···O hydrogen bond closes a six-membered ring. A chain is formed due to aromatic π-π interactions, and a three-dimensional framework structure is formed by a combination of C-H···O and C-H···π(arene) hydrogen bonds. Compound (IIa) was formed not only regioselectively but also chemoselectively, with just the triple bond reacting and the double bond remaining unchanged. Compound (IIa) crystallizes as N-H···O hydrogen-bonded dimers stabilized by aromatic π-π interactions. Dimers of (IIa) are connected into a chain by weak C-H···π(arene) interactions.

Intensification of a Reaction by the Addition of a Minor Amount of Solvent: Diels-Alder Reaction of 2H-Pyran-2-ones with Alkynes

Diels-Alder transformation of substituted 3-benzoylamino-2H-pyran-2-ones 1 with a variety of alkynes 2 under microwave (MW) irradiation in a closed system can be intensified in a novel way by addition of a minor amount of butan-1-ol. When the reagents are not volatile under the used conditions, the reactions do not seem to be influenced by the addition of butan-1-ol, as demonstrated by the cycloaddition of a fused 2H-pyran-2-one 5 with N-ethylmaleimide (6) giving adduct 7.