Photochemische Reaktionen. 65.(vorläufige) Mitteilung. Spezifisch π → π*‐induzierte Photoisomerisierungen von 10‐Dimethoxymethyl‐Δ^1,9‐octal‐2‐on. Ein photochemischer Zugang zu [4.4.3]‐12‐Oxapropellan‐Derivaten

Abstract

Herrn Dr. Roger Firnzenich zu seinem 65. Geburtstag gewidmet (31. VIII. 71) 65. (vorlaufige) Mitteilung [1]Summary. Selective n + z* excitation of the %,@-unsaturated enone 1 in hydrocarbon solvents resulted in a deconjugation reaction to 3, reminiscent of results previously reported for similar systems [2], whereas the photoreactivity of 1 in alcohol solvents a t wavelengths > 3400 A was so small that only product 4 has been identificd as yet.

Visible‐Light‐Driven Competitive Stereo‐ and Regioisomerization of (E)‐β‐Nitroenones

“…As hinted above, the photoreactivity of α,β‐unsaturated ketones has been investigated in the past; [13] in particular, Fong and co‐workers [13b] pointed out the role of singlet and triplet excited states (n‐π*) in the deconjugation pathway. The photoreactivity of 1 a – 6 a has been summarized in Scheme 2.…”

Photochemistry of 4-isobutyl-4-methyl- and 4-(2-methoxyethyl)-4-methyl-2-cyclopentenone. Stereochemical effects in intramolecular abstraction of hydrogen by the .beta.-carbon atom of cyclopentenones

“…2.29 (m, 1 ), 2.18 (dd, J = 3,18 Hz, 1 ), 2.13-1.36 (m, 7 ), 1.73 (d,y = 18 Hz, 1 ), 1.14 (s, 3 ), 1.01 (d,J = 1 Hz, 3 H); 13C NMR W¡ 26.0 (q), 26.8 (d), 29.7 (q), 37.7 (t), 39.0 (s), 43.6 (t), 46.0 (t), 4.71 (m, 1 ), 2.24-1.71 (m, 6 ), 2.13 (s, 2 ), 1.77 (m, 3 ), 1.05 (s, 3 H).…”

“…3-Isobutyl-3-methylcyclopentanone (6). A solution of isobutylmagnesium bromide was prepared from magnesium (5.35 g, 0.22 g-atom) and isobutyl bromide (27.4 g, 0.20 mol) in ether (160 mL).…”

“…3-Isobutyl-3-methylcyclopentanone (6) and Labeled Ketones 39d and 40d from Keto Alcohols 39a,c and 40a,c. Diastereomeric keto alcohols 39a,c and 40a,c were ketalized using the procedure for keto urethanes 39b and 40b.…”

1971–1976 – Profiting from a New Beginning in Geneva

“…internal conversion, S 2 → S 1 , and intersystem crossing, S 1 → T 1 , are not always the processes to occur prior to chemical reaction. Some of these investigations were followed up after their initiation at ETH, [1][2][3] and most were eventually concluded after my move from Geneva to the Max-Planck-Institut für Strahlenchemie in Mülheim an der Ruhr in fall 1976. [4][5][6][7][8] One focus was on the excited state-selective reactions which we had come upon when still at ETH.…”