Photochemistry of bicyclo[2.2.2]octenones: an uncommon oxidative decarbonylation

Lee, Tsung-Ho; Rao, Praveen; Liao, Chun‐Chen

doi:10.1039/a901182j

Cited by 18 publications

(7 citation statements)

References 10 publications

(6 reference statements)

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“…Following the general procedure (method A), MOB 6a generated in situ from phenol 3 and allyl alcohol (1a) was reacted and the crude residue was subjected to column chromatography (EtOAc/hexanes ) 1:3) to give 10a (38% yield) as a colorless liquid: IR (film) 2975, 1749 cm -1 ; 1 H NMR (400 MHz, CDCl3) δ 6.20 (dd, J ) 8.2, 6.4 Hz, 1H), 5.97 (dd, J ) 8.2, 1.7 Hz, 1H), 4.13 (dd, J ) 8.0, 3.6 Hz, 1H), 3.80 (d, J ) 8.0 Hz, 1H), 3.51 (s, 3H), 3.31 (ddd, J ) 6.0, 4.6, 1. 8 Hz,1H),1H), 1.78 (dd, J ) 13.2, 10.0 Hz, 1H), 1.63 (d, J ) 13.2 Hz, 1H), 1.30 (s, 3H); 13 C NMR (100 MHz,CDCl3) δ 202.6,136.4,129.2,100.7,74.1,51.4,47.2,42.8,38.9,37.3,16.8; MS (EI, 12 eV) m/z (relative intensity) 166 (M + -CO, 60), 151 (8), 134 (5), 125 (100), 119 (4), 107 (26), 91 (18), 79 (9), 74 (3), 43 (3); HRMS (EI) calcd for C10H14O2 (M + -CO) 166.0994, found 166.0998.…”

Section: Methodsmentioning

confidence: 99%

“…Recently, highly functionalized tricyclic [ m .2.2.0] ring systems were achieved via diastereoselective IMDA reactions of MOBs in our laboratories . On the other hand, the IMDA adducts can undergo interesting and useful photochemical reactions, such as oxadi-π-methane rearrangement 8 to provide a variety of compounds with potential synthetic utility. 6b, The IMDA adducts obtained from analogous tandem processes were employed as advanced intermediates in the formal synthesis of (±)-reserpine 10 and the total syntheses of a clerodane diterpenic acid 11 and (±)-pallescensin B 12 in our laboratories. In addition to our efforts, various IMDA adducts of MOBs have been employed as key intermediates in the total syntheses of (±)-xestoquinone 5d,13 and (±)-halenoquinone .…”

Section: Introductionmentioning

confidence: 99%

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Intramolecular Diels−Alder Reactions of Brominated Masked o-Benzoquinones. A Detour Method To Synthesize Highly Functionalized Oxatricyclic [m.3.1.0] Ring Systems from 2-Methoxyphenols

et al. 2002

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Intramolecular Diels-Alder (IMDA) reactions of masked o-benzoquinones (MOBs) 5a-d to 7a-d and 17a-d to 19a-d generated in situ from 2-methoxyphenols 2-4 and 14-16, respectively, in the presence of alkenols 1a-d, resulting in highly functionalized oxatricyclic [m.3.1.0] ring systems are described. The MOBs 5a-d to 7a-d underwent the IMDA reactions to furnish the adducts 8a-d, 10a-d, and 12a-d (direct method) in poor yields with the concomitant formation of considerable amounts of unexpected byproducts 9a-d, 11a-d, and 13a-d, respectively. To avoid the formation of byproducts and to improve the yields of the desired cycloadducts, a detour method comprising sequential bromination of 2-methoxyphenols 2-4, tandem oxidative acetalization-Diels-Alder reaction, and debromination has been developed. The oxidation of bromophenols 14-16 in the presence of alkenols 1a-d produced the corresponding MOBs 17a-d to 19a-d, which underwent cycloaddition to afford the cycloadducts 20a-d to 22a-d, respectively, as sole products in good to high yields in a highly regio- and stereoselective manner. Treatment of the bromoadducts 20a-d to 22a-d with tributylammonium formate-palladium reagent produced the corresponding debrominated products 8a-d, 10a-d, and 12a-d in high to excellent yields. In general, the latter oxatricycles were obtained in higher overall yields via the detour method than those via the direct method.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Intramolecular Diels−Alder Reactions of Brominated Masked o-Benzoquinones. A Detour Method To Synthesize Highly Functionalized Oxatricyclic [m.3.1.0] Ring Systems from 2-Methoxyphenols

et al. 2002

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“…This is convenient, because b,g-unsaturated ketones usually have a weak absorption band of the n-p Ã transition state at $300 nm, while the acetone used as solvent is the main light absorber and thus an efficient sensitizer. The irradiation of ketones 51a,b in acetone furnished the ODPM rearrangement products 52a,b in good yields (Scheme 4.23) [32]. Acetophenone is also a convenient sensitizer for the ODPM rearrangement.…”

Section: Oxa-di-p-methane Rearrangement Of Bg-unsaturated Ketones Anmentioning

confidence: 99%

Formation of a Three‐Membered Ring

Tsuno

2009

Handbook of Synthetic Photochemistry

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“…As part of our continuing studies on the photochemistry of bicyclo[2.2.2]octene derivatives, , we have contemplated a study of the photochemical behavior of compounds 1 − 3 containing multiple chromophoric systems that share a common alkene moiety (Figure ). The objective is to study the chemoselectivity of the ODPM rearrangement and to determine the influence of interfering chromophoric systems on it.…”

Section: Introductionmentioning

confidence: 99%

Photochemistry of Bicyclo[2.2.2]oct-7-ene-2,5-diones and the Corresponding 5-Hydroxyimino and 5-Methylene Derivatives

Yang

Rao

et al. 2003

J. Org. Chem.

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Synthesis and photochemistry of several title compounds 1-3 containing multiple chromophoric systems are described. The Diels-Alder reactions of 2,6,6-trimethylcyclohexa-2,4-dienone (5) with acetylenes 6a-d provided the adducts 7a-d, which upon hydrolysis furnished the desired bicyclo[2.2.2]octenediones 1a-d. Oximes 2a-d were prepared from diones 1a-d by treatment with hydroxylamine hydrochloride in pyridine. 5-Methylenebicyclo[2.2.2]oct-7-en-2-ones 3a-d were obtained via chemoselective Wittig reaction of the corresponding diones 1a-d. Bicyclo[2.2.2]octenediones 1a-c underwent chemoselective oxa-di-pi-methane rearrangement under sensitized conditions and suffered formal ketene extrusion upon direct irradiation. Direct irradiation of 1d afforded 11d via formal ketene extrusion but under sensitization it remained unchanged. Oximes 2a-d suffered ketene extrusion upon direct irradiation and E/Z isomerization under sensitized conditions. On the other hand, 5-methylenebicyclo[2.2.2]oct-7-en-2-ones 3a-d generally underwent 1,3-acyl shift. The plausible courses of all these photochemical processes are discussed.

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Photochemistry of bicyclo[2.2.2]octenones: an uncommon oxidative decarbonylation

Cited by 18 publications

References 10 publications

Intramolecular Diels−Alder Reactions of Brominated Masked o-Benzoquinones. A Detour Method To Synthesize Highly Functionalized Oxatricyclic [m.3.1.0] Ring Systems from 2-Methoxyphenols

Intramolecular Diels−Alder Reactions of Brominated Masked o-Benzoquinones. A Detour Method To Synthesize Highly Functionalized Oxatricyclic [m.3.1.0] Ring Systems from 2-Methoxyphenols

Formation of a Three‐Membered Ring

Photochemistry of Bicyclo[2.2.2]oct-7-ene-2,5-diones and the Corresponding 5-Hydroxyimino and 5-Methylene Derivatives

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