Photochemical Reactions. 80th Communication [1]. Preliminary report on the photolysis of (E) – Dehydro‐β‐ionone‐epoxide

Abstract

Summary. Irradiation of a pentane solution of (E)-dehydro-8-ionone-epoxide (1) with light from a medium pressure mercury lamp using acetone as filter led to formation of the isomers 2, 3, 4 and 5 by novel photochemical processes.Irradiation of a 0.04 m pentane solution of (E)-dehydro-8-ionone-epoxide (1) [2] using medium pressure mercury lamp and acetone as filter led t o a mixture of products consisting mainly of the isorners 2, 3, 4 and 5 shown in Scheme 1 2 ) . The structures assigned were inferred from spectroscopic data and confirmed by degradation 3). Irradiation of 1 in pentane with a low pressure lamp in quartz apparatus (1 = 254 nm) until 50% conversion gave 2 as the only major product. Subsequent irradiation did not increase the yield of 2 but led to a more complex reaction mixture. Isomers 2-5 gave correct analyses for C1,H,,O, and mass spectra in accord with the proposed structures,

Photochemical reactions. 134th Communication. Photochemistry of 5,6‐epoxy‐5,6‐dihydro‐3,4‐methano‐β‐ionone: Influence of a cyclopropane ring on the reactivity of an ylide intermediate

“…By Cyclopropanation of (E)-4-(1',2'-Epoxy-2'.6',6'-Trirnethyl- 1 ) . According to the procedure described in [S], a solution of (E)-l [18] (15.6 g, 75.7 mmol) in benzene (60 ml) and CH,I, (25 ml, 310 mmol) and Cu-powder (40 g, 630 mmol) was refluxed for 4 days. After filtration over Celite and chromatography of the mixture (SiO,; Et,O/hexane 1:2), two fractions were obtained, the first (3.02 g) contained 80% of (E)-5 (14%) and the second (1.58 g) contained 40% of 7 (4%).…”

Photochemische Reaktionen. 118. Mitteilung [1] Zur vinylogen β‐Spaltung von Enonen. UV.‐Bestrahlung von 4‐(3',7',7'‐Trimethyl‐2'‐oxabicyclo [3.2.0]hept‐3'‐en‐1'‐yl)but‐3‐en‐2‐on

“…Das Rohprodukt wurde an Si02 in Hexan/Essigsaureathylester 5: 1 bis zu 1: 1 chromatographiert") und die Mischfraktionen durch wiederholte Saulenchromatographie") (SO,; CH2ClzlAther 5: 1 bis zu 2: 1, dann CH2C12/CH30H 50: 1 sowie Aceton/ Benzol1:4) aufgetrennt. Produktverteilung: 3% 4 [6], 3% 5 [2], 4% 6, 4% ( 4 -7 , 4% ( 2 ) -7 , 3% 8 (Reinheit ca. SO%), 4% (Z)-9 sowie 4% 10.…”

“…-'H-NMR. (360 MHz; CDC13): 1,13 (d, J = 17,3, iiberlagert durch s bei l,14, ein H-C(6)); 1,14 und 1,28 (24 2 H3C-C (7)); 2.00 (dxd, J1= 17,3, J2=8,6, das zweite H-C(6)); 2,05 und 2,17 ( 2~, CH3CO); 3,58 ( d x d x d x d ,J1=9,2,J2=8,6,J3=2,3,Jd=2,2,); 3,98 ( d x d , J1=9,2, J2=1,9, H-C(4)); 4,14 ( d x d x d , J1=4,5, J2=2,2, J3= 1,9, H-C(3)); 5,37 ( d x d ,Jl=4,5,J2=2,3,). -I3C-NMR.…”

“…(Reinheit: ca. 95%): 2,18 (3, 3 H-C(1)); 2,33 (d, J = 1, H3C-C(S')); 6,OO (dxqa, J l = 3 , J 2 = I , H-C(4')); 6,43 (d, J = 3 , H-C(3')); 6,J= 15,5,fiA=6,43,hE=7,05, und H-C(4)). ~ I%-NMR.…”

“…Umsatz bestrahlt. Produktverteilung2): 3% 4 [2] [6], 3% 5 [2], 4% 6, 4% (E)-7, 4% (2)-7, ca. 3% 8, 4% 9 sowie 4% 10 (s. Schemata 1 und 2).…”