Efficient Oxidative Conversion of Aldehydes to 2-Substituted Oxazolines and Oxazines Using (Diacetoxyiodo)benzene

Abstract

An efficient synthesis of 2-substituted oxazolines from aldehydes and 2-amino alcohol using (diacetoxyiodo)benzene as an oxidant, is reported. (Diacetoxyiodo)benzene acts as a mild dehydrogenating agent to convert the initially formed oxazolidine from aldehyde and 2-amino alcohol to furnish 2-substituted oxazoline. Similarly, 3-aminopropanol and aldehydes gives the corresponding 2-substituted oxazines.

Chemistry of Polyvalent Iodine

“…Likewise, the preparation of benzopyrano- and furopyrano-2-isoxazoline derivatives from 2-allyloxybenzaldoximes by DIB oxidation,379 the synthesis of various N-substituted indole derivatives via BTI-mediated intramolecular cyclization of enamines,380 the synthesis of 2-substituted benzothiazoles via the oxidative cyclization of thiobenzamides,381 the preparation of 2,3-diphenylquinoxaline-1-oxide from benzil-α-arylimino oximes using DIB,382 the synthesis of 1-(5-aryl-[1,3,4]oxadiazol-2-ylmethyl)-3-(4-methoxyphenyl)-1 H -[1,8]naphthyridin-2-ones by oxidative cyclization of [2-oxo-3-(4-methoxyphenyl)-2 H -[1,8]naphthyridin-1-yl]acetic acid arylidenehydrazides with alumina-supported DIB under microwave irradiation,383 the synthesis of 2,5-disubstituted-1,3,4-oxadiazoles by via BTI-mediated oxidative cyclization of aldazines,384 the preparation of 2-substituted oxazolines from aldehydes and 2-amino alcohols using DIB as an oxidant,385 the synthesis of 3,4-bis(1-phenyl-3-arylpyrazolyl)-1,2,5-oxadiazole- N -oxides by the DIB oxidation of pyrazole-4-carboxaldehyde oximes,386 the synthesis of 2-arylbenzimidazoles from phenylenediamines and aldehydes via a one-step process using DIB as an oxidant,387 the DIB-mediated efficient synthesis of imidazoles from α-hydroxy ketones, aldehydes and ammonium acetate,388 the preparation of dihydrooxazole derivatives by DIB-promoted 1,3-dipolar cycloaddition reactions of phthalhydrazide,389 and the synthesis of seco -psymberin/irciniastatin A via a DIB-mediated cascade cyclization reaction 390. Very recently, Togo and Moroda have reported a DIB-mediated cyclization reaction of 2-aryl- N -methoxyethanesulfonamides using iodobenzene as a catalyst (5–10 mol%) and m -chloroperoxybenzoic acid as the stoichiometric oxidant 391…”

An efficient one-pot synthesis of 2-oxazolines with molecular iodine under ultrasound irradiation

“…Compared with the condensation catalyzed by (diacetoxyiodo)benzene in acetonitrile at room temperature reported in the literature [36], the present procedure offers several advantages including faster reaction rates and higher yields. The reaction of 4-chlorobenzaldehyde (1a) and 4-nitrobenzaldehyde (1f) with 2-aminoethanol in presence of (diacetoxyiodo)benzene in acetonitrile gave corresponding products in 65 and 52 % yields in 8 and 9 h, respectively.…”

“…The reaction of carboxylic acids [12][13][14][15][16][17] or acid derivatives like ester [18][19][20][21][22] with 2-aminoethanol is the most common method for the synthesis of oxazolines. In addition, other substrates such as imidate hydrochlorides [23], N-(2-hydroxyethyl) amides [24][25][26][27][28][29], ortho esters [30], imino ether hydrochlorides [31], aldehydes [32][33][34][35][36][37] and nitriles [38][39][40][41][42][43][44][45][46] have been used to prepare the oxazolines. Despite the potential applications of the reported procedures in the synthesis of 2-oxazoline derivatives, some of them suffered from one or more shortcomings such as prolonged reaction times, expensive catalysts, hazardous reaction conditions, tedious work-up procedures and lack of general applicability.…”

Aliphatic aldehydes in the synthesis of carbo- and heterocycles. Part I. Synthesis of three-, four-, and five-membered rings

“…Studies in this field include search for appropriate catalysts (mostly Lewis acids) and optimal conditions to attain nearly quantitative yield and ensure facile regeneration of the initial aldehyde and subsequent mild oxidation of cyclic products [128][129][130][131][132][133][134][135][136][137][138][139][140][141][142][143]. Under definite conditions, only aldehydes may be converted into the corresponding thio acetals even in the presence of ketones [130].…”