Microwave reactions of 2-amino-2-methyl-1-propanol (2) or 2-aminoethanethiol hydrochloride (4) with readily available N-acylbenzotriazoles 1a-j in the presence of SOCl(2) produced 2-substituted 2-oxazolines 3a-j in 84-98% yields and 2-substituted thiazolines 5a-i in 85-97% yields, respectively. With use of this method chiral oxazoline 6, bisoxazoline 7, bisthiazoline 8, and 5,6-dihydro-4H-1,3-oxazines 9 or 10 have also been prepared in 82-96% yields. These results demonstrate a new application of N-acylbenzotriazoles in the preparation of oxazolines and thiazolines under mild conditions and short reaction times with microwave irradiation.

Microwave reactions of primary and secondary amines with imidoylbenzotriazoles 6a-w gave diversely substituted amidines 7a-Aa in 76-94% yields. Convenient preparations of a variety of amides 5a-Ab (87-96%) and imidoylbenzotriazoles 6a-w (56-95%) have also been developed using microwave irradiation under mild conditions and short reaction times. These results demonstrate further the advantages of microwave synthesis and introduce a new application of imidoylbenzotriazoles in the preparation of polysubstituted amidines.

A general method for the synthesis of 1,5-disubstituted tetrazoles from imidoylbenzotriazoles that involves mild reaction conditions and short reaction times.1,5-Disubstituted tetrazoles are important in biology and medicine as NAD(P)H oxidase inhibitors, 1a glucokinase activators, 1b hepatitis C virus (HCV) serine protease NS3 inhibitors, 1c calcitonin gene-related peptide receptor antagonists, and antimigraine agents. 1d 1,5-Disubstituted tetrazoles are also useful synthetic intermediates 2a for the synthesis of energetic salts, 2b 3,4-dihydropyrimidin-2(1H)-ones, 2c piericidins, 2d (+)-trans-5-allylhexahydroindolizidin-3-ones, 2e acacetin, 2f (+)-strictifolione, 2g vinylsilianes, 2h and leucascandrolide A. 2iThe many published preparative methods for 1,5-disubstituted tetrazoles 3 include reactions of (i) amides with phosphorus(V) chloride or triflic anhydride and hydrogen azide or sodium azide, 4,5 (ii) thioamides with trimethylsilyl azide, 6 (iii) imidoyl chlorides with sodium azide, 7 (iv) ketones with sodium azide 8 or trimethylsilyl azide, 9 (v) oximes with hydrogen azide, 10 (vi) nitriles with alkyl chlorides and trimethylstannyl azide 11 or with alkyl azides, 12 (vii) nitrilium triflates with sodium azide, 13 and (viii) amidrazones with dinitrogen tetroxide or nitrous acid (Scheme 1). 14 Further preparations involving conversion of substituted tetrazoles into 1,5-disubstituted tetrazoles include (ix) alkylation of 5-substituted tetrazoles 15 and (x) coupling of substituted 5-chlorotetrazoles with organozinc 16 or vinylboronic acid (Scheme 1). 17However, many of these reported methods suffer from one or more of the following drawbacks: (i) long reaction times, (ii) the use of toxic and/or explosive reagents, (iii) tedious workup and low yields, (iv) high temperatures, (v) the formation of inseparable regioisomers, and (vi) the use of uncommon starting materials. Thus, a mild and efficient method is required for the preparation of 1,5-disubstituted tetrazoles.Imidoylbenzotriazoles, which are stable to water and easily prepared, 18 are useful substitutes for imidoyl chlorides and we now report that they can be used to synthesize 1,5-disubstituted tetrazoles in high yield under mild conditions.Imidoylbenzotriazoles 2a-p (Table 1) were prepared from the corresponding secondary carboxamides 1a-p and benzotriazoles using Method A: oxalyl chloride and pyridine or Method B: thionyl chloride under microwave (80 W/80°C) following a literature procedure. 18 Thus, 2a-d were prepared following Method A and 2e-o were prepared following Method B. The compound 2p was prepared using Method B, but at 60 W/60°C (Scheme 2). Imidoylbenzotriazoles 2h and 2p were novel and were completely characterized. Scheme 2 Preparation of imidoylbenzotriazoles 2a-pImidoylbenzotriazoles are stable in water and do not react with sodium azide at room temperature. Although the reaction of N-[1-(1H-benzotriazol-1-yl)ethylidene]-4-methylaniline (2b) with sodium azide in the presence of trifluoroacetic acid (1 equiv) to give 5-methyl-1-(4-methyl...

A facile method for the activation of hydroxy-substituted carboxylic acids using benzotriazole chemistry without prior protection of the hydroxy substituents is presented. The N-acylbenzotriazole intermediates 2a-g, 6a-d, and 9a-c have been used for high-yielding synthesis of both aliphatic (3a-l) and aromatic (7a-h, 10a-f) hydroxy carboxamides. High yields of aromatic hydroxy esters 12a-h and 13a-i were obtained using either neat alcohols in neutral microwave conditions or nucleophilic alkoxides and the intermediate N-(arylacyl)benzotriazoles. Moderate yields were obtained in the case of aliphatic hydroxy esters 11a,b and thiolesters 11e-g from the intermediates 2a-c.

Reported are syntheses of several new monomer precursors of cathodically coloring conducting polymers (CPs), based on a propylene dioxythiophene skeleton. These are shown to yield CPs—both as homopolymers and as copolymers—that are nearly “perfectly” matched electrochemically and electrochromically with a set of anodically coloring poly(aromatic amines), for use in dual‐polymer electrochromic lenses. Resulting dual‐polymer electrochromic lenses display very high light/dark contrast (typically up to 70/7% or 50/0.5% Transmission (integrated over visible spectrum, vs. air reference), Haze < 2%, very high cyclability (> 10 K cycles), multiyear shelf life, appealing transparent to dark‐blue‐black transition, and excellent optical memory. Dramatic lowering of switching time, from 8 to < 1 s, is demonstrated using unique applied‐potential algorithm resident on inexpensive Microcontroller chip. Working, practical dual‐polymer electrochromic spectacles are demonstrated with electrochromic lenses retrofitted to spectacles meeting ANSI Z87.1, GL‐PD 10–12 (U.S. military) specifications. These incorporate photosensor, rechargeable Li battery, Microcontroller, allow for automated operation. Ab‐initio‐design spectacles, also conforming to above specifications, are also demonstrated, with components seamlessly hidden within frame. To the best of our knowledge, the electrochromic lenses and sunglasses reported herein represent the best visible‐region electrochromic performance for dual‐polymer CP electrochromic systems to date and the first practical implementation in working sunglasses. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41043.

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The ability of immobilized lipase B from Candida antarctica (Novozym 435) to catalyze the direct esterification of citric acid (CA) and monoglyceride (MG) for citrate esters of monoacylglycerols (CITREM) preparation was investigated. The effects of substrate concentration, molecular-sieve amount, substrate molar ratio, reaction temperature, time, and enzyme load on the conversion of CA in the reaction were investigated. Enzyme screening and the effect of solvent on the esterification were also investigated. RSM was used to optimize the effects of the reaction temperature (45-558C), the enzyme load (6-10%; relative to the weight of total substrates), and the reaction time (24-48 h) on the conversion of CA. Validation of the RSM model was verified by the good agreement between the experimental and the predicted values of CA conversion. The optimum preparation conditions were as follows: CA concentration 0.12 mol/L, molecular-sieve 120 g/L, molar ratio of MG/CA 2:1, temperature 54.188C, enzyme load 9.0% (relative to the weight of total substrates), and reaction time 47.5 h. Under the suggested conditions, the conversion of CA was 77.4%. Repeated reaction tests indicated that Novozym 435 could be used eight times under the optimum conditions with 92% of its original catalytic activity still retained.