J. Am. Chem. Soc.

1972

DOI: 10.1021/ja00757a033

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Photochemical transformations of small-ring heterocyclic compounds. XXXII. Photochemical transformations in the 9-heterobicyclo[3.3.1]nonenone system

Albert Padwa¹,

Angelo Battisti²

Abstract: non-6-en-2-one (1) and its 9-oxa analog have been found to rearrange principally to methyl 5,6-dihydro-2//-pyran-2-propionate derivatives upon irradiation in methanol. When the irradiation of the thia system was carried out in deuteriomethanol, the product formed was found to have incorporated the deuterium atom in the thiapyran portion of the molecule. Irradiation of the oxa analog in deuteriomethanol, however, gave ester which had the deuterium atom located adjacent to the carbonyl group. This result indicat… Show more

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K[endo-h-c(3)]/kk[exo-d-c(3)] = 93/7; K[exo-h-c(3)j/k;[end1

€T-c(z) -C(3) -C(z') -C(3')1

-[(Cyczohex-2'-en-yl)-rnetl~yl]-5-(cyczohex-2"-en-yl)-e-~en1

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1972

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Cited by 23 publications

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“…2 H-C(4), 2 H-C(7) und 2 H-C(8)) : 2,02 (s, encio -H3CCOO-C(G)) ; 3,97 (w, w1jz ca. 9, H-C(1)) ; 4,24,45 (112 (5 Hauptsignalc), H-C(5)); 1,93 (d, J g e z o , 7 e n d o = 12, ferner JJg,6ezo und J6ezo,7ezo j e 5, 139 (9), 129 (31,5), 112 (62,5), 111 (loo), 95 (21) 158 ( 3 4 , 144 (60,5), 141 (99), 140 (18,5), 123 (25,5), 113 (29,5), 98 (loo), 84 (74,5), 81 3600, 3430, 1720s, 14653600, 3430, 1720s, , 14423600, 3430, 1720s, , 13823600, 3430, 1720s, , 13653600, 3430, 1720s, , 13133600, 3430, 1720s, , 1245s, 1130, 2 H-C(4) und 2 H-C (8) sowie exo-H-C(6)); 2,08 (s, exo-H&COO-C (7)); 2,61 (.z, w1/2 ca. 10, endo-HO-C(2)); 3,7-4,2 (117, H-C(l), H-C(5) und exo-Ii-C(2)) ; 5,45 ( k Jgeso, 7 e 2 n~o u n d J 7 e n d~, s~~~ je 11, fernerJ7en~o, s e n d o .…”

Section: K[endo-h-c(3)]/kk[exo-d-c(3)] = 93/7; K[exo-h-c(3)j/k;[endunclassified

Photochemische Reaktionen. 87. Mitteilung. Zur Photolyse von 9‐Oxabicyclo[3.3.1]nonan‐2‐on

1976

Helvetica Chimica Acta

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Photolysis of Bicyclo[3.3.1]nonan‐2‐one. Disproportionations, the secondary processes available to the acyl‐alkyl biradical b (X(9) = 0) formed from 9‐oxabicyclo[3.3.1]‐nonan‐2‐ones a (X(9) = 0) in a primary photochemical process by α‐cleavage (Norrish type I cleavage) were studied. Special attention was paid to the selectivity between the two possible H‐abstractions: the one at C(3) (→ ketene c, X(9)= 0) and the other one at C(8) (→ alkenal d, X(9) = 0) and to the selectivity of the H‐abstraction at a definite methylene group (C(3) or C(8)). In the case of ketene formation (→ c, X(9) = 0) the specificity of the insertion of the migrating H‐atom at C(1) was studied. endo‐6‐Hydroxy‐9‐oxabicyclo[3.3.1]nonan‐2‐one (6) and derivatives of it (7, 8, 16, 17, 19, 21, 30 and 38) as well as exo‐6‐hydroxy‐9‐oxabicyclo[3.3.1]‐nonan‐2‐one (41) and its derivative 42 were used as substrates. UV.‐irradiation of 6 in benzene yielded 1,5‐dioxa‐2‐cis‐decalone (44) by way of a ketene g (R = H) as demonstrated by the photolysis of 7 (→ 45), 8 (→ 43), and 17 (→ 47). Specific labellings with deuterium proved that H‐abstraction occurs intramolecularly at C(3) (e.g. 16 → 54; 6 + 16 → 44 + 54), that one of the H‐atoms at C(3) migrates specifically to C(1) (21 → 55; 19 → 56), endo‐H–C(3) being favored by a factor of 6. The abstraction showed an unexpected primary isotope effect of about 2. UV‐irradiation of 41 in benzene yielded in addition to the expected 1,5‐dioxa‐2‐trans‐clecalone (63) about 3% of an isomeric compound 67 which probably results from H‐abstraction at C(8) (→ alkenal 65) followed by cyclisation.

“…2 H-C(4), 2 H-C(7) und 2 H-C(8)) : 2,02 (s, encio -H3CCOO-C(G)) ; 3,97 (w, w1jz ca. 9, H-C(1)) ; 4,24,45 (112 (5 Hauptsignalc), H-C(5)); 1,93 (d, J g e z o , 7 e n d o = 12, ferner JJg,6ezo und J6ezo,7ezo j e 5, 139 (9), 129 (31,5), 112 (62,5), 111 (loo), 95 (21) 158 ( 3 4 , 144 (60,5), 141 (99), 140 (18,5), 123 (25,5), 113 (29,5), 98 (loo), 84 (74,5), 81 3600, 3430, 1720s, 14653600, 3430, 1720s, , 14423600, 3430, 1720s, , 13823600, 3430, 1720s, , 13653600, 3430, 1720s, , 13133600, 3430, 1720s, , 1245s, 1130, 2 H-C(4) und 2 H-C (8) sowie exo-H-C(6)); 2,08 (s, exo-H&COO-C (7)); 2,61 (.z, w1/2 ca. 10, endo-HO-C(2)); 3,7-4,2 (117, H-C(l), H-C(5) und exo-Ii-C(2)) ; 5,45 ( k Jgeso, 7 e 2 n~o u n d J 7 e n d~, s~~~ je 11, fernerJ7en~o, s e n d o .…”

Section: K[endo-h-c(3)]/kk[exo-d-c(3)] = 93/7; K[exo-h-c(3)j/k;[endunclassified

Photochemische Reaktionen. 87. Mitteilung. Zur Photolyse von 9‐Oxabicyclo[3.3.1]nonan‐2‐on

1976

Helvetica Chimica Acta

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Photolysis of Bicyclo[3.3.1]nonan‐2‐one. Disproportionations, the secondary processes available to the acyl‐alkyl biradical b (X(9) = 0) formed from 9‐oxabicyclo[3.3.1]‐nonan‐2‐ones a (X(9) = 0) in a primary photochemical process by α‐cleavage (Norrish type I cleavage) were studied. Special attention was paid to the selectivity between the two possible H‐abstractions: the one at C(3) (→ ketene c, X(9)= 0) and the other one at C(8) (→ alkenal d, X(9) = 0) and to the selectivity of the H‐abstraction at a definite methylene group (C(3) or C(8)). In the case of ketene formation (→ c, X(9) = 0) the specificity of the insertion of the migrating H‐atom at C(1) was studied. endo‐6‐Hydroxy‐9‐oxabicyclo[3.3.1]nonan‐2‐one (6) and derivatives of it (7, 8, 16, 17, 19, 21, 30 and 38) as well as exo‐6‐hydroxy‐9‐oxabicyclo[3.3.1]‐nonan‐2‐one (41) and its derivative 42 were used as substrates. UV.‐irradiation of 6 in benzene yielded 1,5‐dioxa‐2‐cis‐decalone (44) by way of a ketene g (R = H) as demonstrated by the photolysis of 7 (→ 45), 8 (→ 43), and 17 (→ 47). Specific labellings with deuterium proved that H‐abstraction occurs intramolecularly at C(3) (e.g. 16 → 54; 6 + 16 → 44 + 54), that one of the H‐atoms at C(3) migrates specifically to C(1) (21 → 55; 19 → 56), endo‐H–C(3) being favored by a factor of 6. The abstraction showed an unexpected primary isotope effect of about 2. UV‐irradiation of 41 in benzene yielded in addition to the expected 1,5‐dioxa‐2‐trans‐clecalone (63) about 3% of an isomeric compound 67 which probably results from H‐abstraction at C(8) (→ alkenal 65) followed by cyclisation.

“…3.l]nonan-2-onen (a), sowohl mit X(9) = S (Charge-Transfer-Anregung, (C,-S)-Spaltung: Padwa & Battisti [14] sowie eigene Arbeiten [15]) als auch mit X(9) = SO (Stereomutation: eigene Arbeiten [16] …”

Section: )unclassified

“…-C(4'j, -C(5') und -C(6') sowie H-C(1'); 3,62/((ta, j l , z a und J~, 2 1 , je 6,5, 2 I-I-C(l (ll), 182 (4,.5j, 179 (2,5), 166 (2,5), 141 (2,5), 124 (37), 109 (3), 103 (7), 96 (loo), 83 (86), 82 (95,5), 75 (25,5), 67 (39), 55 (80), 41 (37,5), 29 (14); . Zu einer Lijsnng von 1,434 g (9,31 mniol) 3-(C~clohex-3'-en-~-l)-propions~ure (7) [21] …”

Section: €T-c(z) -C(3) -C(z') -C(3')unclassified

“…: 140 (M+, 8,5), 122 (13), 107 (13,5), 96 (16), 94 (41,5), 93 (36,5), 81 (67), 80 (96), 79 (loo), 77 (14), 67 (32,5), 54 (37,5), 43 (16,5), 41 (28), 39 (19,5), 31 (9,5), 29 (7,5) Dcssen 3, , 2710s, 17285, 1652, 1453, 1436, 1412, 1388, 1360, 1337, 1302, 1185, 1168, 1140, 1096, 1040, 947, 925, 909, 870, 835, 649s. - [3.3.7]nona~z (14). 446 nig (1,858 mmol) Alkohol 13 [23] wurden bei 0" in 13 ml Pyridin gelost, rnit 0,3 ml (ca.…”

Section: )unclassified

“…91 (10,5), 81 (100). 79 (33), 67 (14,5), 5. 5 (10,5), 53 ( I S ) , 43 ( 3 ) , 41 (24), 39 (7,5), 29 (43, 27 (4) 219.5, 2165219.5, , 2100219.5, , 1712s, 1470219.5, , 1450219.5, , 1443219.5, , 1417219.5, , 1332219.5, , 1263219.5, , 1230219.5, , 1172219.5, , 1124219.5, , 1096219.5, , 1080219.5, , 1013219.5, , 1008 1,5-2,7/~, 2 H-C(3), --C(4), --C(6), -C(7) und -C (8) sowie H-C(1) und 918, 876, 862, 721, 700, 682, 670.…”

Section: -[(Cyczohex-2'-en-yl)-rnetl~yl]-5-(cyczohex-2"-en-yl)-e-~enunclassified

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Photochemische Reaktionen. 86. Mitteilung [1]. Zur Photolyse von Bicyclo[3.3.1]nonan‐2‐on

Stingelin-Schmid²,

1976

Helvetica Chimica Acta

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Photolysis of Bicyclo[3.3.l]nonan-2-one. -Summary. Disproportionations to the unsaturated aldehydes 2 and 3 or the ketene 4, the secondary processes available to the acyl-alkyl hiradical b[X(9) = CHz] formed from bicyclo[3.3.l]nonan-2-one (1) in a primary photochemical process by cc-cleavage (Norrish type I cleavage), were studied.If the acyl-alkyl biradical b [X(9) = CH2] has a lifetime sufficient to permit rotation around one or several bonds before H-transfer occurs, considerations about the energetically most favored conformations of b allow to deduce the following preference for intramolecular H-abstraction: at C(9) (f + unsaturated aldehyde 2) > at C ( 3 ) (l+ kctene 4) > a t C(8) ( i + unsaturated aldehyde 3). If H-transfer takes place very quickly, following an energetically favored small conformational change of the acyl-alkyl biradical, one expects H-abstraction a t C(9) and/or C ( 3 ) to be preferred over that at C(8). These predictions were fully confirmed by the experiments. UV. irradiation of bicyclo[3.3.l]nonan-2-one (1) in n-pentane gave a complex mixture of the unsaturated aldehyde 2 and products of further photochemical reactions of 2: 43 and 44,45 and 46, 49-52, and 54-57 (see below). Photolysis of 1 in methanol, however, yielded 82% of 2 and 1,2% of ester 23, the final product from ketene 4 formed by trapping of a solvent molecule.UV. irradiation of the 9,9-dideuterio-ketone 20 confirmed the intramolecular D-abstraction at C(9) (+ unsaturated aldehyde 21) and consequently the H-abstraction at C(9) in the sequence 1 + 2. That either of the two H-atoms at C(9) in 1 can be abstracted was demonstrated by the photolysis of the C(9)-epimeric 9-acetoxy-bicyclo[3.3.l]nonan-2-ones 24 and 25 in methanol. I n both cases the unsaturated aldehyde 26 was formed, which corresponds to abstraction of H-C(9)c (7) and H-C(9)C(3)15), respectively.In separate UV. irradiation experiments it was shown that the products accompanying the unsaturated aldehyde 2 (photolysis of 1 in n-pentane) were formed in the following ways: diene 43 and acetaldehyde (44) from 2 by intramolecular y-H abstraction followed by Norvish type I1 reaction; the spiro-alcohols 45 and 46 from 2 by intramolecular y-H abstraction followed by ring closure to cyclobutanols; the oxetanes 49-52 by cycloaddition (Patenzo-Biichi reaction) of acetaldehyde (44) to 3-methylidene-cyclohexene (43) ; the aliphatic alcohols 54-57 by addition of acetaldehyde (44) to n-pentane, i.e. H-abstraction from the hydrocarbon solvent followed by combination of the radicals thereby formed.Einleitung . -Bei n,n*-angeregten Cycloalkanonen ist die sog. a-Ketonspaltung

Neue Reaktionen mesoionischer 1,3‐Dithiolone mit Singulett und Triplett‐Sauerstoff

¹

,

²

,

Schoy-Tribbensee

³

1981

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Photochemisch erzeugter Singulett-Sauerstoff vereinigt sich mit den 2,5-Diaryl-l,3-dithiolylium-4-olaten 1 a, b in Gegenwart von Methanol zu Phenylglyoxylsaure-methylester (6) und den Disulfiden 421, b als Ergebnis einer Spaltung der primar gebildeten [3 + 21-Cycloaddukte vom Typ 2.Wahrend 1 a, b keine Reaktivitat gegeniiber Triplett-Sauerstoff entfalten, reagiert das mesoionische 1,3-Dithiolon 1 c mit Triplett-Sauerstoff bei Raumtemperatur unter Bildung eines 2,5,7-Trithiabicyclo[2.2.1] heptanon-Derivats 10, dessen Konstitution durch Rtintgenstrukturanalyse gesichert ist. New Reactions of Mesoionic 1,3-Dithiolones with Singlet and Triplet OxygenPhotochemically generated singlet oxygen combines with the 2,5-diaryl-l,3-dithiolylium-4-olates 1 a, b in the presence of methanol to produce methyl phenylglyoxylate (6) and the disulfides 4a, b as a result of a fragmentation of the primarily formed [3 + Z]cycloadducts of type 2. Whereas l a , b show no reactivity towards triplet oxygen, the mesoionic 1,3-dithiolone l c reacts with triplet oxygen at room temperature with formation of a 2,5,7-trithiabicyclo[2.2.l]heptanone derivative 10, whose structure is established by an X-ray crystal structure analysis.In jungster Zeit haben sich die mesoionischen 1.3-Dithiolone vom Typ 1' -4) als wertvolle Syn-[hone in der Heterocyclen-Chemie e r~i e s e n * -~) .Beispielsweise eroffneten ihre 13 + 21-Cycloadditionen an Heterodoppelbindungssysteme interessante synthetische Zugange zu neuen heterobiund heterotricyclischen Systemen2-10). Noch nicht untersucht sind dagegen die Reaktionen von 1 mit Sauerstoff, uber die wir nachstehend berichten. A. Addition von Singulett-Sauerstoff an 1,3-Dithiolylium-4-olate 1Bestrahlte man die rnit Sauerstoff begaste BenzoVMethanol-Lbsung aus 2,5-Diphenyl-1,3-dithiolylium-4-olat (1 a) in Gegenwart von Rose bengale als Triplett-Sensibilisator bei 10°C rnit Natrium-Licht ()L = 589 nm), so bleichte die tiefviolette Eigenfarbe von 1 a aus, und die Aufarbeitung lieferte neben 99% kristallisiertem 4a noch 28% Bliges 6. Die Produkte 4a und 6 erwiesen sich rnit authentischem Dibenzoyldisulfid bzw. Phenylglyoxylsaure-methylester als identisch.Die analoge photosensibilisierte Reaktion des mesoionischen 1,3-Dithiolons 1 b mit Sauerstoff ergab den bekannten Ester 6 (43%) sowie das Disulfid 4b (WVo), dessen Konstitution rnit den spektroskopischen Daten (s. Experimenteller Teil) in Einklang war.

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