Photoaddition of allenes to benzene

Arene–Alkene Cycloaddition

“…Allene and 1,2-cyclononadiene both reacted with benzene predominantly in a para fashion, although in very low yields …”

“…118 Allene and 1,2-cyclononadiene both reacted with benzene predominantly in a para fashion, although in very low yields. 178 Dimethylallene 371 reacts with phenylpyrrolium perchlorate 370 mainly in the para mode (Scheme 93). 179 On the other hand, unsubstituted allene gave various rearranged products and only 15% of ortho adduct (together with 5% of its cyclooctaetraene rearranged isomer).…”

The meta photocycloaddition of arenes to alkenes

“…other products are dimers of norbornene after dechlorination a:b = 2:1 (15% benzene in alkene); stereochemistry was not determined; structures were assigned on the basis of the similarity of the NMR spectra with those of the adducts from norbornene ipa = 0.16; ipb = 0.11; Mothers = 0.01, 0.01 (1.1 M benzene + 3.5 M alkene in isooctane); the other products are probably dimers of cycloheptene ipa = 0.31; y>b = 0.07; vVtho = 0.09 (1.1 M benzene + four adducts, ratio 2:12:6:1 (5% v/v allene in benzene); 22,44,46 the para adduct (4ir + 2ir) is the major product; the meta adduct is the second most abundant product the major product is 22, 46 the para adduct (4ir + 2ir); para:meta = 6:1; no ortho cycloaddition (10% v/v alkene in benzene) the exo-ortho adduct is the major product; ftorth0 = 0.3; 15, 30, 47-50 fta = 0.075; ft, = 0.05; <pc = 0.008 (estimated); fta = 0.03 (1.1 M benzene + 3.5 M vinyl ether in isooctane) ortho:meta = 2.7:1, ortho adduct is exo; a:b:c = 1.25:1.1:1.0 48-50 a:b:c = 1:1:0.5; ortho adduct is also formed 50 a:b:c:d = 20:1:1:6 (equivolume mixture of benzene and 19, 27, 43, vinyl acetate); the endo ortho adduct is also formed; 51, 52 ftmeta = 0.22; ftorth0 = 0.03 (1.1 M benzene + 3.5 M vinyl acetate in isooctane) ftortho = 0.04; (ft"eta = 0.03 (1.1 M benzene + 3.5 M alkene 30 in isooctane) ortho:meta = 7.5:1; endo-ortho > exo-ortho 43,48,50 (equivolume mixture of addends) the meta adducts and the para adduct are only minor 48-50, 53 products; exo-ortho is the major adduct (95%); ftortho 0.7; ftmeta + para 0.01 (1.1 ^4 benzene -I-3.5 M alkene in isooctane) fta = 0.31; (ft, -0.07; ftexo-ortho -' 0.21; ftpara = 0.04 48, [54][55][56] (1 M dioxole in benzene) reaction mixture contains meta adducts (40%), two exo-ortho adducts (40%) and a para adduct (16%); -0.5 (1 M dioxole in benzene, ref 54); ratio of meta adducts is a:b:c:d = 56:31:11:2 (1.3 M benzene + 0.4 M dioxole in cyclohexane) a:b = 96:4; the major product is the exo-ortho adduct; ^ortho 0.39, (Pmeta 0.12; ^para ^0.005 (1 M dlOXOle in benzene) meta adducts are reported to be formed; ortho:meta = >4:1 structures are unpublished meta adducts are reported to be formed; ortho:meta = >9:1 structures are unpublished meta adducts are reported to be formed; ortho:meta = >9:1 structures are unpublished a:b = 5:1; meta:para = 6:1 (1.0 M alkene in benzene) d-chlorostyrenes + tetrachlorocyclobutanes (together 30%) + two 1:1 adducts in a ratio of 1:2.5; the minor adduct is ortho and the major adduct is meta; it is thermally unstable and undergoes 1,3 and 1,5 Cl shifts meta adducts (mixture of isomers) constitute 17% of product mixture; the major photoprocess is para addition (4ir + 4ir) (benzene:butadiene = 10:1) meta adducts (mixture of isomers) constitute 32% of product mixture; para addition (At + 4t) is the major other photoprocess (benzene:isoprene = 10:1) a, b, and c are the major meta adducts; a para adduct (4ir + 4ir) is the fourth major adduct; substitution products are formed in minor amounts (0.24 mol diene in 37% para adduct (4ir + 4-ir); 21% meta adducts; 66 42% nonvolatile material (0.24 mol diene in 1.2 mol benzene) the...…”

The photoaddition of 1,3-diketonatoboron difluorides with benzene derivatives

“…Chemical shifts (6) for 'H and 13c spectra were reported in ppm with reference to tetramethylsilane. The coupling constants are reported in Hz.…”