Herrn Prof. T. Reichstein zum 80. Geburtstag gewidmet (9.1X.77) Photoinduced Vinylogous B-Cleavage of Epoxy-enones of the Ionone Series SummaryThe photochemistry of the a,/?-unsaturated y , 6-epoxy-enones 1-3 is determined by: (i) C(y)-0-scission of the epoxide (vinylogous /?-cleavage of Type A ) ; (ii) C (y)-C(G)-cleavage of the oxirane (vinylogous P-cleavage of Type B); (iii) (E/Z)-isomerization of the enone chromophore. In contrast, 4 with tertiary C (6) shows no Type B cleavage.Type A cleavage is induced both by n,n*-and n,n*-excitation and arises probably from the TI-state, but Type B cleavage is observed only on x, n* -excitation and represents presumably a S2-reaction.On Type A cleavage 1-4 undergo 1,2-akyl-shifts to 1,5-dicarbonyl compounds (15-18, 25-28, 34 and 35) or rearrange to dihydrofuranes (7 and 30). The isomerization 1 -+ 7 proceeds by a stereoselective [ 1,3]-sigmatropic shift.On Type B cleavage 1-3 isomerize to a bicyclic enol-ether (8, 29) or to a monocyclic enol-ether (9; product of a homosigmatropic [ 1,5]-shift) or undergo fragmentation to isomers such as allenes 10,22 and 31 or cyclopropenes 11 and 21.The non-isolated, unstable (Z)-epoxy-enones# 14, 19, 24 and 38 isomerize by fragmentation to the furanes 12,23,33 and 39 respectively, on contact with traces of acid or by heating. However, for 19 and 4, Type B cleavage may lead to the furanes 23 and 39.On UV. irradiation of the epoxy-enone 4 the initially formed (EI2)-isomers 34 and 35 yield on n, n*-excitation the enones 37 and 40 by a vinylogous P-fragmentation. In addition, on n, n*-excitation 34 isomerizes to 35, which decarbonylates exclusively to the enone 37.The reactions of 1-4 with BF, . 0 (C2H5), were also studied (see appendix). The epoxy-enones 1 and 2 isomerize by an 1,2-alkyl shift in good yield to the 1,4-') Auszugsweise vorgetragen von B. Frei an der Herbstversammlung der Schweizerischen Chemischen Gesellschaft in Bern am 7.Oktober 1977. Schema 3 15(E); 16(Z) 1 7 ( E ) ; 18(Z) 7 12 0 i a 3 4 7 n r n 0 1>347nm/He 6 ) 193 Wurde die Eduktlosung parallel zur Photolyse im Dunkeln aufbewahrt, so trat keine Reaktion ein. 24) Das Rohprodukt stellte der 'H-NMR.-Analyse zufolge ein ausserst komplexes Gemisch dar. Neben dem AB-System des Eduktes liessen sich eindeutig nur H-C(8') und -C(Y) des Dihydrofurans 30 (d bei 5,46 und 5,65 ppm) identifEieren. Fur das Furan 33 konnten weder die Methylsingulette bei 1,31 und 1,98 pprn, noch die olefinischen Wasserstoffatome (AB-System bei 6,20 ppm) nachgewiesen werden. 2s) 25-28 und 31 konnten auch gas-chromatographisch nicht in reiner Form abgetrennt werden.

On '71, n*-excitation the 6-keto-enones 5-8 are isomerized to compounds B (18, 22, 26, 28) via 1,3-acyl shift and to compounds C (19, 23, 27, 29) via 1,2-acyl shift, whereas the p, y , 6, E-unsaturated ketone 9 gives the isomers 32 and 33 by 1,2-and 1,5-acyl shift, respectively. Furthermore, isomerization of 6 to 24, dimerization of 8 to 30 and addition of methanol to 8 (8 -+ 31) is observed. Unlike 7 and 8 the acyclic ketones 5, 6 and 9 undergo photodecarbonylation on '71, 71"-excitation Evidence is given, that the conversion to B as well as the photodecarbonylation of 5, 6 and 9 arise from an excited singulet state, but the conversion to C as well as the dimerization of 8 from the T,-state.

Es wird die Herstellung einiger 1‐Methyl‐4‐phenyl‐piperidin‐(4)‐alkylsulfone beschrieben. Durch Behandlung mit 50‐proz. Schwefelsäure wird die Alkylsulfon‐Gruppe in ähnlicher Weise wie bei den von Klenk und Mitarbeitern(1) hergestellten Benzhydryl‐alkylsulfonen(2) unter Bildung einer Doppelbindung am quaternären C‐Atom des Piperidinringes abgespalten. Die hergestellten Alkylsulfon‐Verbindungen sind zum Teil ebenso gut analgetisch wirksam wie das Dolantin. Beim Ersatz der Carbäthoxy‐Gruppe des Dolantins durch die Äthylsulfon‐Gruppe bleibt die analgetische Wirkung voll erhalten, während die Toxizität auf einen vierfach geringeren Wert absinkt. Dies stimmt mit den von Klenk und Mitarbeitern(1) in der Amidonreihe gemachten Beobachtungen überein.

Hans Herloff Inhoffen zum 70. Geburtstag gewidmet (15.111.76) Photolysis of (E)-5-Isopropyl-6-methyl-5,6-epoxy-hept-3-en-2-on. -Summary. This paper continues the series of investigations of the photochemistry of d,P-unsaturated y, d-epoxyketones, by examinating the photochemical behaviour of the aliphatic vinylogous epoxy-ketone 1, the chromophore of which is structurally similar to that of y,&epoxy-(E),P-ionone (44).On n,n*-excitation (A = 254 nm) 1 isomerizes mainly to the enol-cther 2 and gives as minor products the isomeric dihydrofurane 3, the 1,5-diketones 4 and 5 and the 1,3-diketone 6. To a smaller extent, 1 also undergoes photofragmentation to the furane 7, the allenyl-ketone 8 and the cyclopropenyl-ketone 9. On n,n*-excitation (A > 347 nm) 1 yields the photoisomers 3, 4, 5 and in traces the hydroxyallenyl-ketone 14, but no fragmentation products. It is shown that on irradiation at A = 254 nm the 1,5-diketone 4 isomerizes to 5, 6 and 15 and photodecarbonylates to the B. y-unsaturated ketone 16.The isomers 3, 4 and 5, obtained both from n,n*-and n,n*-excitation, rcpresent products of cleavage of the C(y)-0-bond in 1. The enolether 2, on the other hand, formed only by 3z,x*-excitation, results from cleavage of the C(y)-C(6)-bond.Finally, the fragmentation products 7, 8 and 9, which could be detected only on n,n*-excitation, may arise from a common intermediate g t) h.

This paper continues the series of investigations of the photochemistry of a , punsaturated y , S-epoxyketones by examining the hitherto unknown photochemical behaviour of a, P-acetylenic-y , S-epoxy-ketones. As model compound, the aliphatic epoxy-ynone 7 (thermally stable at 180") was synthesized (Scheme 1). It can be converted with BF30(C2H5)2 in good yields to the 1,Sdiketone 8, the yne-1,4diketone 49 and in small amounts to the fluorhydrine 50 (Schemel4).On n, n*or n, n*-excitation, 7 shows mainly cleavage of the C (y)-0-bond to give a diradical a (Scheme 1 I), whose ultimate fate is strongly solvent dependent. In acetonitrile a mainly rearranges to the 1,5-diketone 8 and, to a smaller extent, shows fragmentation to acetone and formation of polymers. Except for small amounts of the dimeric products 9A, 9 B and biphenyl, the same compounds are obtained in benzene. In cyclopentane, however, a gives only little of 8, and mainly a plethora of compounds formed by a radical process like H-abstraction from solvent, incorporation of cyclopentylradicals, dimerization and fragmentation reactions (9A, 9B, 11-20) (Scheme 3). Irradiation of 7 in propan-2-01 or in dioxane yields products of analogous radical processes as well of photoreduction (Scheme 4). However, the analogous epoxyenone 32 gives mainly products of photoisomerizations without interference by the solvent [6].On photochemical excitation in acetonitrile, the 1,5-diketone 8 shows unspecific decomposition, but in cyclopentane it yields the reduction products 12, 26A, 26 B, 27,28 plus cyclopentylcyclopentane (15) (Schemeb). R = H 3 R = A c 4 R = A c 5 R = HAls Modellverbindung wahlten wir das Epoxy-inon 7 (s. Schema I ) . Ausgehend von Diisopropylketon (1) war die noch unbekannte Verbindung 7 uber sechs Syntheseschritte in einer Gesamtausbeute von 60% gut erhaltlich. Das Epoxid erwies sich thermisch als relativ stabil. Bei einstundigem Erhitzen in Cyclopentan auf 180" wurde 7 nicht nachweisbar verandert und konnte gas-chromatographisch ohne Zersetzung (1 1% QF-1, 175 ") isoliert werden. 2. Bestrahlungsversuche. -2.1. Photolysen von 7. Der Epoxyinon-Chromophor von 7 zeigt n, n*-Absorption mit einem Maximum bei 227 nm (F: = 8380) und, getrennt davon, n, n*-Absorption mit einem Maximum bei 312 nm (E = 28). Bei den Photolysen strahlte man daher selektiv in je einen dieser Absorptionsbereiche ein Schema 2 9 (A+B) 10 Lsgm.: @ CH3CN