Reactions of benzvalene with tetracyanoethylene, 2,3-dichloro-5,6-dicyano-p-benzoquinone, chlorosulfonyl isocyanate, and sulfur dioxide. Evidence for concerted 1,4-cycloadditions to a vinylcyclopropane system

Abstract

The reaction of bennalene (4) with tetracyanoethylene (TCNE) affords a mixture of tetracyclo[ 3.3.0.02~4.03~6]o~tane derivative 5, tricycl0[3.3.0.0~~~]oct-7-ene derivative 6, and tricycl0[3.3.0.0~~~]oct-6-ene derivative 7. By means of dideuterated benzvalene 4a and the solvent effect on the ratio of the products the mechanisms have been studied. Accordingly, the formation of the main products 5 and 6 involves zwitterionic intermediates, which arise from electrophilic attack of TCNE at the olefinic portion of 4. The third compound 7 is thought to be produced in a concerted 1,4-addition of TCNE to the vinylcyclopropane moiety of benzvalene (4). Treatment of 4 with 2,3-dichloro-5,6-dicyano-p-benzoquinone gives rise to a 1:l adduct, which is structurally analogous to TCNE adduct 7 and which is most probably formed in a one-step process as evidenced by the positions of the deuterons when 4a was utilized. In a reinvestigation of the reaction between chlorosulfonyl isocyanate and 4 the new compounds 18a, a 4-azatricycl0[3.3.0.0~*~]oct-6-en-3-one derivative, and 19, an 8-azatetracycl0[4.2.0.O~~~.O~~~]octan-7-one derivative, have been discovered in addition to the known products 2a and 3a. Even at low temperatures benzvalene (4) and sulfur dioxide react to give a mixture of the four-membered ring sulfone 23 and the sultine 24, with the ratio being dependent on the solvent polarity. That 23 is not the precursor of 24 follows from rate measurements, according to which the rearrangement 23 -24 is much slower than the formation of 24 from 4 and SO2. The experiment utilizing dideuterated benzvalene 4a has revealed a competition between two processes, a concerted 1,4-addition of SO2 to the vinylcyclopropane system of 4 yielding 23 and an electrophilic attack of SO2 at C-1 (C-6) of 4 with formation of the zwitterion 25 with a sulfinate function and an allyl cation moiety. The latter species cyclizes with almost the same rates via an oxygen atom or the sulfur atom to give rise to 2 4 and another portion of 23, respectively. In the stepwise processes TCNE and SO2 approach 4 at different sites. This phenomenon is discussed in terms of the HSAB principle. Due to its high-lying H O M O benzvalene (4) reacts with numerous electrophiles.2 In most cases the attack takes place at the double bond since the H O M O is largely localized there.3q4 Exceptions are the protonation5-' and the mercuration8 generating products, which indicate addition of the electrophile to the bicycle[ 1.1 .O] butane skeleton. Also, Ag' and several metals interact with the u system and catalyze automerizations of 4 and, finally, isomerizations to benzene and fulvene, respe~tively.~ Katz and co-workers have studied the reactions of 4 with 4-Tetracyanoethylene Results. Tetracyanoethylene (TCNE)'* resembles PTADI2gJ3 and CSII4 in that it frequently gives rearranged adducts with ~ ~-(12) (a) Loffler, H. P.; Martini, T.; M U S S~, H.; Schroder, G. Christl, Brunn, and Lanzendorfer L . 5 L.0 3.5 3.0 2.5 (17) Prinzbach, H.; Hagemann, H.; Hartenstein, J. H.; Kitzing, R. C...

SO2 Uptake on Oleic Acid: A New Formation Pathway of Organosulfur Compounds in the Atmosphere

“…Under our conditions (nonpolar surface), radical, rather than ionic reactions might be promoted, leading to diradical intermediates (Figure ). These kinds of intermediates have been proposed for photoreactions of SO 2 with alkenes, and their interaction with oxygen can lead to formation of reactive oxygen species (ROS). , Organosulfur products could be generated via addition of SO 2 to the double bond, , whereas the OA oxidation products could be explained by radical chain reactions triggered by ROS. Indeed, the observed products at m / z 297.244 (C 18 H 33 O 3 – ) and m / z 187.098 (C 9 H 15 O 4 – ) are common lipid oxidation products .…”

Daytime SO 2 chemistry on ubiquitous urban surfaces as a source of organic sulfur compounds in ambient air

“…The addition of SO 2 to the double bond of the organic compounds (fatty acids and PAHs) (see Discussion) available on the urban grime could explain the formation of these CHOS compounds. For example, a cycloaddition of SO 2 to the C═C of the PAHs compounds may occur, leading to the formation of cyclic CHOS compounds (47)(48)(49). The observed CHOS could also be organosulfates with a hydroxyl group (OH) and a C═C bond or cycle in the side chain (46).…”

3-Methylenetricyclo[3.1.0.02,6]hexane, a Tricyclic Isomer of Toluene: Synthesis and Addition onto Tetracyanoethylene

“…[6,25Ϫ28] In the cases of benzvalene [26] and homobenzvalene, [27] a homo DielsϪAlder reaction, considered to occur concertedly, onto a vinylcyclopropane subunit takes place (among other processes). Although 7 possesses a vinylcyclopropane moiety, such a reaction appeared unlikely, since the product would be a derivative of (E)-cycloheptene.…”