84449-81-0Relevant articles and documents
Hepta(methoxycarbonyl)cycloheptatriene halo derivatives
Platonov,Okonnishnikova,Levina,Tomilov, Yu. V.
, p. 241 - 245 (2015/10/05)
A reaction of potassium hepta(methoxycarbonyl)cycloheptatrienide with chlorine and bromine gave high yields of the corresponding chloroand bromohepta(methoxycarbonyl)cycloheptatrienes; the fluoro derivative was obtained by the exchange reaction of the corresponding bromide with silver fluoride. In contrast to the mentioned halides, the iodo derivative has proved unstable. Thermolysis of bromohepta(methoxycarbonyl)cycloheptatriene was studied, as well as its conversion to the azido and methoxy derivatives upon treatment with NaN3 or methanol.
Retro-Diels-Alder reaction of 4H-1,2-benzoxazines to generate o-quinone methides: Involvement of highly polarized transition states
Sugimoto, Hiromichi,Nakamura, Satoshi,Ohwada, Tomohiko
, p. 10088 - 10095 (2008/04/12)
(Chemical Equation Presented) Here, we describe mechanistic studies of the retro-Diels-Alder reaction of 4H-1,2-benzoxazines bearing various substituents on the benzene ring. 4H-1,2-Benzoxazines are very simple, but quite new, heterocyclic compounds that afford substituted o-quinone methides (o-QMs) through retro-Diels-Alder reaction under mild thermal conditions. The resultant o-QMs undergo Diels-Alder reaction in situ with dienophiles to give phenol and chroman derivatives. The mechanism of the generation of o-QMs has been little studied. Our experimental and density functional theory (DFT) studies have yielded the following results. (1) The generation of o-QMs, i.e., the retro-hetero-Diels-Alder reaction of 4H-1,2-benzoxazines, is rate determining, rather than the subsequent Diels-Alder reaction of the resultant o-QM with dienophiles. (2) The reaction rate is strongly influenced by the electronic features of substituents and the polarity of the solvent. The reaction proceeds faster in a polar solvent such as dimethyl sulfoxide, probably because of stabilization of the electronically polarized TS structure. (3) The reactions show characteristic positional effects of substitution on the benzene ring. While an electron-withdrawing group such as CF3 at C5, C6, or C7 positions decelerates the reaction, the same substituent at C8 accelerates the reaction, compared with the reaction of unsubstituted 4H-1,2-benzoxazine. In particular, substitution at C5 significantly decelerates the reaction as compared with the unsubstituted case. This is due to the difference in the inductive effect of CF3 at the different positions. Similar positional effects occur with a halogen (Cl) and a nitro group. All these data support the involvement of polarized TS structures, in which the O-N bond cleavage precedes the C-C bond cleavage.
Reaction of stabilised phosphorus ylides with nitrogen dioxide
Aitken, R. Alan,Karodia, Nazira
, p. 251 - 254 (2007/10/03)
The reaction of the stabilised ylides 14-23 with an excess of NO2 in CH2Cl2 at room temperature gives different results depending on the structure of the starting ylide. The monacyl ylides 14-16 give the corresponding α-oxo nitriles 4 together with Ph3PO · HNO3 (24) which has been fully characterised for the first time. Under the same conditions, the ylide 18 gives 2,4-dinitrobenzonitrile (26), Ph3PO, and benzoic acid. The other ylides examined all give 24 together with a variety of other products.
Process for producing cyanoformate esters
-
, (2008/06/13)
Alkyl, aralkyl or aryl cyanoformate esters having from one to 20 carbon atoms are prepared by anhydrously reacting stoichiometric amounts of the corresponding alkyl, aralkyl or aryl haloformate and an organosilyl nitrile in the presence of a catalytic amount of a tertiary amine base, preferably 1,4-diazabicyclo?2.2.2!octane, in the absence or presence of an inert solvent. The reaction is conducted at a temperature of from about -30° C. to 70° C., preferably at from about 5° C. to 30° C.
1,2λ3,3λ3-AZADIPHOSPHOLE EIN AROMATISCHES RINGSYSTEM MIT CIS-P=P-DOPPELBINDUNG 1λ3ρ3,λ3ρ3-DIPHOSPHOLE
Maerkl, G.,Dietl, S.,Ziegler, M. L.,Nuber, B.
, p. 5867 - 5870 (2007/10/02)
By reaction of 1,2,4,5-tetrazinedicarboxylates with 4 mole tert-butylphosphaethyne the title compounds are formed in an unusual reaction sequence.
