- Synthesis of 2-bromo-1-aryl-1H-indenes via a Ag(I) promoted domino 2π-electrocyclic ring-opening/4π-electrocyclization reaction of 1,2-diaryl substituted gem-dibromocyclopropanes
-
2-Bromo-1-aryl substituted indenes can be synthesized from 1,2-diaryl substituted gem-dibromocyclopropanes via a domino reaction sequence. The cascade reaction involves silver(I) promoted ionization and 2π-disrotatory electrocyclic ring-opening, followed by a 4π-conrotatory electrocyclic ring closing reaction of the allylic carbocation intermediate. Reaction conditions utilize silver tetrafluoroborate (AgBF4) in dichloroethane at 65 C. Selectivity effects for the electrocyclization were also studied. The 2-bromoindenes can be further functionalized using cross-coupling reactions, such as the Suzuki-Miyaura protocol. The alkene π-bond of the indenes can also be isomerized to give the thermodynamically more stable 2-bromo-3-aryl-1H-indene isomers using triethylamine in dichloromethane at room temperature.
- Rosocha, Gregory,Batey, Robert A.
-
p. 8758 - 8768
(2013/09/23)
-
- Divergent oxidative rearrangements in solution and in a zeolite: Distal vs proximal bond cleavage of methylenecyclopropanes
-
Irradiation of 9,10-dicyanoanthracene (DCA) or p-chloranil in the presence of E-1-benzylidene-2-phenylcyclopropane (E-5) in CH2CI2 causes E-5 to undergo methylenecyclopropane rearrangement. An adduct, Z-7, between DCA and 5 firmly supports the involvement of a bifunctional trimethylenemethane radical cation. In contrast, incorporation of E-5 into HZSM-5 produces trans,trans-1,4-diphenyl-1,3-butadiene radical cation sequestered in the HZSM-5 interior, tt-8·+ @ HZSM-5, identified by ESR and diffuse reflectance spectroscopy. In addition, low yields of tt-8, its cis, trans-isomer (ct-8), and 1-phenyl-1,2-dihydronaphthalene (9) were isolated from the supernatant solution. The sharp contrast between the photoinduced electrontransfer reaction with photosensitizers in solution and the spontaneous reaction with redox-active acidic zeolite offers the prospect of further zeolite-induced regiodivergent reactions in a range of additional substrates.
- Ikeda, Hiroshi,Nomura, Tsuyoshi,Akiyama, Kimio,Oshima, Mitsuhiro,Roth, Heinz D.,Tero-Kubota, Shozo,Miyashi, Tsutomu
-
p. 14497 - 14504
(2007/10/03)
-
- Biological evaluation of novel cyclopropyl analogues of stilbene, stilbenediol, and phenanthrene for estrogenic and antiestrogenic activity
-
The triphenylethylene-type antiestrogens, such as tamoxifen, are known to be useful in the treatment of estrogen-dependent tumors. However, these compounds display mixed estrogen agonist/antagonist activity which may limit their therapeutic effectiveness. This problem of mixed activity led to the synthesis and identification of a cyclopropyl derivative of cis-stilbene which we have named Analog I. This compound (1,1-dichloro-cis-2,3-diphenylcyclopropane) displayed only antiestrogenic activity in the mouse. The present study was designed to evaluate cyclopropyl derivatives of Analog II for estrogenic and antiestrogenic activity in the rate using the standard 3-d uterotropic assay and the uterine cytoplasmic estrogen receptor assay. Five compounds (B-F) which are cyclopropyl derivatives of stilbene, stilbenediol, and phenanthrene were evaluated in this study. Three of the compounds (B-D) displayed neither estrogenic nor antiestrogenic activity in the rat. The relative estrogenic activities of E and F were 11.3 and 1.5%, respectively, of diethylstilbestrol in the uterotropic assay, and 39 and 6.2%, respectively, of estradiol in the estrogen receptor assay. Neither E nor F was found to display antiestrogenic activity in the rat. The results indicate that the relative estrogenic and receptor binding activities of E and F are similar to those previously observed in the mouse, while B-D appear to be inactive in both species.
- Pento,Koenig,Magarian,Kosanke,Gilliland
-
p. 120 - 125
(2007/10/02)
-
- 1,3-Diarylcyclopropenes: Syntheses and a Facile Ene Dimerisation
-
1,3-Diphenylcyclopropene (3) and its p,p'-dichloro- (4a) and p,p'-dimethyl-derivatives (4b), together with the 3-deuteriated derivative (1,3-diphenylcyclopropene) (3-d), have been prepared by dehydro- or dedeuterio-bromination of the corresponding bromocyclopropanes (6), (16a), (16b), and (6-d2) with ButOK in THF at -30 deg C, whereas the p,p'-dimethoxy-derivative (4c) has been prepared in THF at -78 deg C by protonation of 1-lithio-2,3-bis(p-methoxyphenyl)cyclopropene (18), generated from 1-bromo-2,3-bis(p-methoxyphenyl)cyclopropene (17).All the cyclopropenes (3), (3-d), and (4a-c) are stable only in solution at -78 deg C, and are characterised by means of 13C n.m.r. at this temperature.At higher temperatures, the cyclopropenes (3), (3-d), and (4a-c) readily dimerise to afford the cyclopropylcyclopropenes (7), (7-d2), and (19a-c) in quantitative yields, according to an ene reaction pathway.The cyclopropene (3) also undergoes an ene reaction with tetracyanoethylene, dibenzoylacetylene, and dimethyl acetylenedicarboxylate to give the adducts (13), (14a), and (14b) in moderate yields.Kinetic measurements have been carried out for the ene dimerisation of (3) (at -58 deg, -50 deg, -40 deg, and -30 deg C), (3-d) (at -40 deg and -30 deg C), and (4b,c) (at -30 deg C) in THF.The highly negative ΔS(excit.) value (-137 J mol-1K-1 at 25 deg C) and the fairly large kH/kD value (3.1 at -40 deg and -30 deg C) obtained for the dimerisation of (3) support a concerted mechanism for this reaction.The dimerisation rate of (3) at -30 deg C decreases with substitution by electron-donating groups in the following order: (3) (k2=19.0E-4mol-1s-1), (4b) (10.9E-4), and (4c) (8.3E-4).
- Komatsu, Koichi,Niwa, Tadashi,Akari, Hideaki,Okamoto, Kunio
-
p. 2847 - 2881
(2007/10/02)
-
- Stereomutation in the Seyferth Reaction
-
The cyclopropanation reaction between dibromomethylene (:CBr2) from the Seyferth reagent (PhHgCBr3) and electron-deficient alkenes is nonstereospecific.Thus fumaronitrile, styrene-cis-β-d, and trans-1,2-dichloroethene give mixtures of the respective cis a
- Lambert, Joseph B.,Larson, Eric G.,Bosch, Richard J.,Vrucht, Mollie L. E. Te
-
p. 5443 - 5447
(2007/10/02)
-