Reactivity of geometrically constrained cyclopropylcarbinyl systems

Structural effects in solvolytic reactions. 16. The effect of conformation of the cyclopropyl, phenyl, and isopropyl substituents on their electronic contributions to the electron-deficient center

“…However, two methyl substituents effectively block this conformation 5'c, greatly reducing the electronic contributions from the cyclopropyl substituents.4k Indeed, from a study of the reactivity of geometrically constrained cyclopropylcarbinyl systems as a function of angle, the reactivity (ranging over 11 powers of ten) of cyclopropylcarbinyl cations was shown to be a continuous function of the geometry between the vacant p orbital and the cyclopropyl ring. 35 The authors further noted that the cyclopropylcarbinyl cation with 60°g eometry, approximately the geometry of a bicyclobutonium ion, is considerably less stable than the ion with 30 or 0°( i.e., bisected) geometries.35 Moreover, solvolyses of optically active cyclopropylmethylcarbinyl derivatives do not yield optically active products.36 A -bridged intermediate would have been expected to retain asymmetry.…”

Charge-transfer photochemistry from the donor-acceptor complexes of anthracenes with tetranitromethane

“…However the absorption of light by anthraldehyde (Pyrex filter) did result in the formation of an unidentified substituted 9,10-dihydroanthraldehyde product. This product ['H NMR 6 6.06 (s, 1 H), 7.25-7.5 (m, 8 H), 10.90 (s, 1 H)] was neither 3 nor the photodimer of anthraldehyde [5 5.51 (s, 1 H), 6.64 (d, 2 H ,J = 7.3 Hz), 6.86 (td, 2 H ,J = 7.4, 1.3 Hz), 6.92 (td, 2 H ,J = 7.4, 1.1 Hz), 7.04 (dd, 2 H ,J = 1.1, 7.3 Hz), 10.12 (s, 1 H)]. radicals 2 may be diverted by oxidation with TNM,44 which occurs in competition with the trapping by N02.…”

Cyclopropanation of some simple olefinic compounds. By-product formation in excess Simmons-Smith reagent

“…3-Buten-l-ol (6) was prepared by reduction of 3-butenoic acid (1) with lithium aluminum hydride: bp 28 °C (12 mm); n23o 1.4197 [lit.9 bp 115 °C (770 mm), n2bd 1.4182], Treatment of 6 with acetic anhydride in pyridine gave 3-butenyl acetate (4): bp 120-123 °C; n2So 1.4240 [lit.10 bp 121-123 and 126 °C, u25d 1.4104 and n20o 1.4105]. Reaction of 6 with diazomethane (prepared from N.jV'-dimethylCV.N'-dinitrosoterephthalamide)11 and a catalytic amount of boron trifluoride etherate in ethyl ether12 afforded 4-methoxy-l-butene (5): bp 70-72 °C; n22D 1.3910 [lit.13 bp 68-69 °C (750 mm), n20D 1.3976]. Methyl 3-butenoate (2) was obtained from 1 and diazomethane: bp 104-106 °C; n23p 1.4070 [lit.13 bp 106 °C (745 mm)].…”

“…4 Similarly, bicyclo[3.2.1] oct-6-en-1 -ol afforded exotricylo[3.3.1.02•4]nonan-1 -ol and the corresponding ethyl and isopropyl ethers. 5 In another work, Majerski and Schleyer6 obtained symmetrical formáis as side products during cyclopropanation reactions of allyl alcohols. In fact, depending upon reaction conditions, some of these alcohols furnished the corresponding formáis predominantly.…”