Convenient Syntheses of 2-Alkyl(Aryl)-4,5-diphenyloxazoles and 2-Alkyl(Aryl)-4-phenyloxazoles

Abstract

a Route A: PhCOCHClPh; route B: -. b The product obtained in 33% yield was indeed a mixture of the oxazole (4%) and a byproduct, benzil (29%). Abstract:The synthetic methods to prepare 2-alkyl(aryl)-4,5-diphenyloxazoles and 2-alkyl(aryl)-4-phenyloxazoles were improved on the basis of a mechanistic study of oxazole formation from α -hydroxy ketones (carboxylic esters of benzoin and phenacyl alcohols). By these methods, seven trisubstituted oxazoles and twelve disubstituted oxazoles of the title compounds were prepared.

Microwave-Assisted Synthesis of 2-Substituted-4,5-diarylimidazoles from Benzoin Carboxylate Derivatives under Solvent-Free Conditions

“…另外, 在前人 [17] 的研究中曾经以冰醋 酸为溶剂, 回流反应 1 h, 以几乎相等的收率(40%左右) 获得目标产物和相应的噁唑. 孙继奎等 [19,20] 在改变上述 合成条件的基础上, 以较高的收率合成了 2-取代-4,5-二 呋喃基噁唑衍生物. 在我们的研究中, 在不使用任何溶 剂的条件下, 将苯偶姻单酯或氯代苯偶姻单酯、醋酸铵 和三氧化二铝充分混合研磨后微波加热 5 或 10 min, 即 可以 38.5%～83.3%的收率获得目标产物 4a～4q (Eq.…”

Synthesis of Novel Derivatives of Benzoxazole in Bis-Ionic Liquid [BDBDIm]Br

“…Generally, the procedures for the synthesis of oxazoles include the Hantzsch reaction, [23] one-pot FriedelCrafts/Robinson-Gabriel synthesis of oxazoles, [24] the dehydration of oxazolines, condensations of substituted amides with phenacyl bromide in EtOH, [25] the Ugi reaction with ammonia as the amine component, [26] reaction of b-(acyloxy)vinyl azides with triethyl phosphite [27] and reaction of benzoin carboxylates with formamide. [28] However, these methods suffer from one or more drawbacks that include use of reactive starting materials, long reaction times, low yields, and harsh reaction conditions. Ionic liquid, proposes a new and environmentally safe approach toward modern synthetic chemistry because of the interesting properties of these types of compounds.…”

Synthesis of α-Acyloxyketone Derivatives <i>via</i> the Platinum-Catalyzed Migration of Propargylic Esters

“…α-Acyloxyketone has also been used as a simple starting material for the stereoselective synthesis of a variety of different structures, including numerous 1,2-diols [4][5][6][7][8] and heterocyclic systems. [9][10][11] Based on the importance of α-acyloxyketones to chemistry, the development of a concise synthetic method for the preparation of α-acyloxyketone derivatives is important. Although a wide variety of synthetic methods have been investigated to date, 12,13) reports pertaining to the direct synthesis of α-acyloxyketone III by the oxidation of alkyne I are rare, most likely because of the difficulties associated with suppressing the over-oxidation of the product and controlling the regioselectivity of the reaction [14][15][16] (Chart 1).…”