24433-81-6Relevant academic research and scientific papers
Indium-mediated one-pot synthesis of benzoxazoles or oxazoles from 2-nitrophenols or 1-aryl-2-nitroethanones
Lee, Jung June,Kim, Jihye,Jun, Young Moo,Lee, Byung Min,Kim, Byeong Hyo
scheme or table, p. 8821 - 8831 (2009/12/26)
One-pot reduction-triggered heterocyclizations from 2-nitrophenols to benzoxazoles and from 1-aryl-2-nitroethanones to oxazoles were investigated. In the presence of indium/AcOH in benzene at reflux, 2-nitrophenols and R-C(OMe)3 (R=H, Me, Ph) produced excellent yields of corresponding benzoxazoles within an hour. Similarly, 1-aryl-2-nitroethanones and Ph-C(OMe)3 in the presence of indium/AcOH in acetonitrile transformed into the corresponding oxazoles with good yields.
115. 1,3-Dipole mit Zentralem S-Atom aus der Umsetzung von Aziden mit Thiocarbonyl-Verbindungen: Eine unerwartete MeS-Wanderung im Abfangprodukt eines 'Thiocarbonyl-aminids' mit Dithiobenzoesaeure-methylester
Mloston, Grzegorz,Romanski, Jaroslaw,Linden, Anthony,Heimgartner, Heinz
, p. 1499 - 1510 (2007/10/02)
Reaction of PhN3 with O-methyl thiobenzoate (11a) and thioacetate (11c) as well as with the dithio esters 11b, d at 80 deg C yields the corresponding imidates and thioimidates 12 (Scheme 3).The formation of 12 is rationalized by a 1,3-dipolar cycloaddition of the azide and the C=S group followed by successive elimination of N2 and S.In the three-component reaction of 11b, PhN3, and the sterically crowded thioketone 1a, 1,2,4-trithiolane 13a and 1,4,2-dithiazolidine 3a are formed in addition to 12b (Scheme 4).The heterocycles 13 and 3a are trapping products of 1a and 'thiocarbonyl-aminide' 5a and 'thiocarbonyl-amidine' 2a (Ar= Ph), respectively (Scheme 6).These 1,3-dipoles are formed as reactive intermediates.Surprisingly, in the presence of catalytic amounts of acids, the major product is the (methyldithio)cyclobutyl thioimidate of type 14 (Scheme 5), formed by an acid-catalyzed MeS migration in dithiazolidine 17.A reaction mechanism is proposed in Scheme 7.
Reaction of Chromium (Fischer) Carbenes and Sulfilimines
Alcaide, Benito,Casarrubios, Luis,Dominguez, Gema,Sierra, Miguel A.
, p. 3886 - 3894 (2007/10/02)
The photochemical reactions of alkoxychromium (Fischer) carbenes and sulfilimines lead to imidates in fair to excellent yields.Aromatic, heteroaromatic, and alkylsulfilimines, the latter bearing functional groups such as cyano, sulfone, ether, ester, and dioxolane groups, gave the corresponding imidates in good to excellent yield.However, acyl- and sulfonyl-substituted sulfilimines did not react with chromium carbenes, except for sulfilimines bearing ethoxycarbonyl and phthalimidylamino groups.A variety of differently substituted chromium carbene complexes bearing alkyl, cycloalkyl, styryl, allyl, and alkynyl groups attached either at the carbene carbon or at the oxygen also gave imidates in good yields.For α,β-unsaturated carbenes, the exclusive 1,2-addition of the sulfilimines nitrogen was observed at room temperature, in contrast to the behavior of other nitrogen nucleophiles which are reported to add in 1,4-fashion under these reaction conditions.In turn, optically active imidates of the type ArN=C(OR*)Me can be prepared efficiently by utilizing the corresponding chiral alkoxy group on the carbene moiety.The reactions above also occur in the dark but reaction times are considerably longer.N-Halosulfilimines reacted with alkoxychromium carbenes to yield N-acylsulfilimines instead of the expected N-haloimidates.Based upon a set of thermal and photochemical reactions between N-haloimidates and diphenyl sulfide in the absence of chromium complexes, the complex (CO)5CrNCMe is proposed to be responsible for this novel reaction of N-haloimidates and diphenyl sulfide.
A new approach to N-aryl- and N-(2-heteroaryl)imidates from chromium carbenes and sulfilimines
Alcaide, Benito,Dominguez, Gema,Plumet, Joaquin,Sierra, Miguel A.
, p. 11 - 12 (2008/10/08)
Irradiation of pentacarbonyl(alkoxymethylcarbene)chromium(0) complexes in the presence of a number of N-aryl- or N-heteroaryl-substituted sulfilimines gives N-aryl- or N-heteroarylimidates in fair to excellent yields.
The Course of the Reaction of Azobenzene with Chromium Carbene Complexes
Hegedus, Louis S.,Lundmark, Bruce R.
, p. 9194 - 9198 (2007/10/02)
The dark reaction between cis-azobenzene and pentacarbonylchromium(0) was followed by 1H NMR spectroscopy.The intervention of two discrete intermediates-thought to be a zwitterion and a metallacycle-was detected.Carrying out the reaction in hexane under a carbon monoxide atmosphere caused the reaction to stop at the metallacycle stage.Photolytic decomposition of this produced 1,3-diazetidinone and imidate products, as well as small amounts of azobenzene. 1,2-Diazetidinone products were thought to result from a primary photoreactionbetween cis-azobenzene and a photogenerated (methoxy)(methyl)ketene chromium complex.
