Thermolysis of the tricyclic 1,2-dioxetanes 3,4:3,4-dipropano-, 3,4-pentano-3,4-propano-, and 3,4-butano-3,4-propano-1,2-dioxetane

Abstract

. Can. J. Chem. 59,851 (1981). The title compounds have been isolated in crystalline form by cyclization of the corresponding bromo-or iodohydroperoxides.The activation parameters for thermolysis are, respectively (E,, kcallmol, AS*, eu): 25.6 f. 0.6,4 f. 2; 29.8 f. 0.4,4 f. 2; 26.3 f 0.5, 1 f 2. Thesinglet '4 and triplet '4 excited state product yieldsproduced on thermolysisofthese compounds are, respectively: 0.01 1, 0.10; 0.0019,O. 18; 0.0013,O. 11. These yields are relative to a value of0.31 for '4 oftetramethyl-1,2-dioxetane. 'The cyclic 1,5-diones from thermolysis of the last two title compounds cyclized before isolation to give the bicyclic hydroxyketones. Thermolysis of 1 ,2-dioxetanes results in the for-3,4-propano-1,2-dioxetane 6, and 3,4-pentanomation of carbonyl cleavage products in quantita-3,4-propano-1 ,Zdioxetane 7 in a test to determine tive yield and in light emission (I), eq. [I]. Both whether the behaviour of 1 is general for dioxetanes n of this structural type. singlet and triplet excited states are formed directly in the primary step of the reaction and the triplet almost always predominates by a large factor in the examples studied to date; for reviews see ref.2. The factors which affect the yield of excited states and the triplet-singlet ratio are the subject of considerable investigation (3). The tricyclic dioxetane 3,4:3,4-dibutano-1 ,Zdioxetane 1, prepared in order to study the effect of the rigidity of its structure on the rate of its thermolysis and the yield of excited states produced, was found to produce much smaller amounts of excited state products than were formed from the mono-and bicyclic dioxetanes trimethyl-, 2, tetramethyl-, 3, and cis-3,4-butano-3,Cdimethyl-1 ,Zdioxetane, 4 (4).The present paper reports the preparation and thermolysis of three other tricyclic dioxetanes, 3,4: 3,Cdipropano-1 ,Zdioxetane 5, 3,4-butano-

Theoretical studies on thermal stability of alkyl-substituted 1,2-dioxetanes

“…Furthermore, and more importantly, the considerably lower yields (Φ T = 1%). 40,41 observed in the decomposition of the tricyclic 1,2-dioxetane 33 (Scheme 3C) might be rationalized by the impossibility of C-C-bond rotation in this derivative, even when this bond is considerably elongated, due to conformational restrictions introduced by the two condensed cyclohexyl rings. Additionally, this derivative shows very low thermal stability even so its peroxidic ring shows small dihedral angle (ω ~ 8 o ), indicating again that the dihedral angle alone is not an indicative for stability and also showing that dioxetane decomposition must not necessarily proceed by C-C-bond rotation, however this movement might be necessary for efficient excited state formation.…”

Vibrational Spectra, Ab Initio Calculations, and Conformations of Bicyclo[3.3.0]oct-1,5-ene

“…and H.H. in Germany using the method described in the literature . Spectra and gas chromatography showed the product to have greater than 98% purity.…”

Mild and chemoselective catalytic deprotection of ketals and acetals using cerium(IV) ammonium nitrate

“…(3aS p ,7aR p )-7a-Hydroxyoctahydro-4H-inden-4-one (32). 25 To a stirred solution of 31 (200 mg, 1.01 mmol) dissolved in acetonitrile (4 ml) was added water (4 ml) and sodium bromate (228 mg, 1.51 mmol). The mixture was heated at 708C and solid CAN (16 mg, 3 mol%) was added.…”