Competition between Cyclization and Dehalogenation in the Photochemistry of Cinnamylphenols with Halogen Substituents at the Phenolic and Styrenic Chromophores

Jiménez, M. Consuelo; Miranda, Miguel A.; Tormos, Rosa

doi:10.1021/jo971621m

Cited by 17 publications

(4 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The spectroscopic data matched those reported in the literature. 49 Data for 3f : 1 H NMR (500 MHz, CDCl 3 ) δ 7.42–7.19 (m, 5H), 6.74 (ddd, J = 9.9, 8.5, 1.3 Hz, 1H), 6.53 (dd, J = 15.9, 1.7 Hz, 1H), 6.36 (dt, J = 15.9, 6.6 Hz, 0H), 4.99 (d, J = 1.3 Hz, 0H), 3.55 (dd, J = 6.6, 1.6 Hz, 2H); 13 C NMR (126 MHz, CDCl 3 ) δ 153.4, 150.1, 137.1, 133.2, 132.4, 130.8, 128.8, 128.3, 127.8, 127.1, 126.5, 117.7, 113.2, 34.1; MS (EI, 70 eV, m / z ) 290 (71, M + + 2), 288 (76, M + ), 209 (93), 131 (24), 118 (39), 115 (45), 104 (100), 91 (82), 77 (41). …”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Catalytic, Enantioselective, Intramolecular Sulfenofunctionalization of Alkenes with Phenols

Denmark

Kornfilt

2017

J. Org. Chem.

View full text Add to dashboard Cite

The catalytic, enantioselective, cyclization of phenols with electrophilic sulfenophthalimides onto isolated or conjugated alkenes affords 2,3-disubstituted benzopyrans and benzoxepins. The reaction is catalyzed by a BINAM-based phosphoramide Lewis base catalyst which assists in the highly enantioselective formation of a thiiranium ion intermediate. The influence of nucleophile electron density, alkene substitution pattern, tether length and Lewis base functional groups on the rate, enantio- and site-selectivity for the cyclization is investigated. The reaction is not affected by the presence of substituents on the phenol ring. In contrast, substitutions around the alkene strongly affect the reaction outcome. Sequential lengthening of the tether results in decreased reactivity, which necessitated increased temperatures for reaction to occur. Sterically bulky aryl groups on the sulfenyl moiety prevented erosion of enantiomeric composition at these elevated temperatures. Alcohols and carboxylic acids preferentially captured thiiranium ions in competition with phenolic hydroxyl groups. An improved method for the selective C(2) allylation of phenols is also described.

show abstract

Section: Methodsmentioning

confidence: 99%

“…The spectroscopic data matched those reported in the literature. 49 Preparation of (E)-2-(3-Phenyl-2-propen-1-yl)-4-chlorophenol (3g). Following general procedure 1, NaH (252 mg, 10.5 mmol), CCl 4 (20 mL), 4-chlorophenol (1.28 g, 10 mmol), and cinnamyl chloride (1.53 mL, 11 mmol) were combined in a 50 mL Schlenk flask.…”

Section: ■ Conclusionmentioning

confidence: 99%

Catalytic, Enantioselective, Intramolecular Sulfenofunctionalization of Alkenes with Phenols

Denmark

Kornfilt

2017

J. Org. Chem.

View full text Add to dashboard Cite

show abstract

“…A representative example of such an effect is provided by trans-4-bromo-2-cinammylphenol, 19a. 34 When 19a is irradiated in benzene, a mixture of the dihydrobenzopyran, 19d, and the solvent-derived cyclic ethers 10c and 10d are obtained. When these results are compared with those obtained for the parent compound 8a, two differences are particularly remarkable: (1) the absence of the 5-membered ring product 19c and (2) the formation of cyclic derivatives related to trans-2-cinnamyl-4-phenylphenol, 10c and 10d.…”

Section: Alternative Reaction Pathwaysmentioning

confidence: 99%

“…A similar pattern is followed by other halogen-substituted cinnamylphenols, such as trans-4-chloro-2-cinammylphenol, 20a, trans-2-[3-(4-bromophenyl)-2-propenyl]phenol, 21a, and trans-2-[3-(4-chlorophenyl)-2-propenyl]phenol, 22a. 34 Introduction of chlorine or bromine into either the phenolic or the styrenic rings of a bichromophoric cinnamylphenol produces a decrease in the corresponding singlet excited state energies. When such energies lie above those required to cleave the carbon-halogen bond, photodehalogenation (eventually followed by solvent addition) efficiently competes with photocyclisation.…”

Section: Alternative Reaction Pathwaysmentioning

confidence: 99%

Proton, electron and energy transfer processes in excited phenol–olefin dyads

2005

Self Cite

View full text Add to dashboard Cite

Dyads containing phenol and olefin subunits are versatile models for the investigation of proton, electron and energy transfer processes. As they are readily accessible, a number of analogues (allylphenols, cinnamylphenols and derivatives) have been prepared with a wide range of photophysical and photochemical properties. By means of appropriate structural modification of a very simple initial structure, it is possible to reproduce, at will, different types of behaviour. In addition to providing valuable fluorescence emission data, these systems are chemically productive, giving rise to irreversible photoreactions that constitute a fingerprint for the mechanism involved. They include photocyclisation to 5- and 6-membered ring cyclic ethers, Z/E isomerisation, di-pi-methane rearrangement, formation of ortho-quinone methides, photohydration and photodehalogenation. This rich photochemistry is highly sensitive to the microenvironment experienced, as indicated by the dramatic modifications observed within cyclodextrin cavities. Intramolecular OH...pi interactions, both in their ground and excited states, play a key role in the interesting properties of 2-allylphenol derivatives. This is supported by experimental data and also by theoretical calculations.

show abstract

Tautomeric Equilibria and Rearrangements Involving Phenols

Koblik¹

2009

Patai's Chemistry of Functional Groups

View full text Add to dashboard Cite

Introduction Tautomerism in Phenols Rearrangements of Phenols Rearrangements of O ‐Substituted Phenol Derivatives Rearrangements of Functionalized Arenes Rearrangements of Non‐Aromatic Carbocycles Rearrangements of Heterocyclic Compounds

show abstract

Competition between Cyclization and Dehalogenation in the Photochemistry of Cinnamylphenols with Halogen Substituents at the Phenolic and Styrenic Chromophores

Cited by 17 publications

References 15 publications

Catalytic, Enantioselective, Intramolecular Sulfenofunctionalization of Alkenes with Phenols

Catalytic, Enantioselective, Intramolecular Sulfenofunctionalization of Alkenes with Phenols

Proton, electron and energy transfer processes in excited phenol–olefin dyads

Tautomeric Equilibria and Rearrangements Involving Phenols

Contact Info

Product

Resources

About