Observation of the 1,4 biradical in the Paterno-Buchi reaction

Freilich, Steven C.; Peters, Kevin S.

doi:10.1021/ja00410a062

Cited by 103 publications

(41 citation statements)

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“…It follows that the lifetime of the C-O-C-C biradical on T 1 is long. This is consistent with experimental observations of the C-O-C-C intermediate [47] and that stereochemistry in alkene is lost by internal rotations of the long-lived C-O-C-C species on T 1 . We suggest alternative escaping pathways from there through S 1 /T 1 -MSXs.…”

Section: -Msxsupporting

confidence: 92%

“…In this study, a photoaddition reaction between an aldehyde (or ketone) and an alkene known as Paternò-Büchi (PB) reaction [42][43][44][45] is considered. Its mechanism has been studied extensively both experimentally and theoretically [46][47][48][49][50][51][52][53][54]. Thus, this reaction is ideal for the present purpose of benchmarking the applicability to photochemical addition reactions.…”

Section: Introductionmentioning

confidence: 99%

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Exploring Pathways of Photoaddition Reactions by Artificial Force Induced Reaction Method: A Case Study on the Paternò–Büchi Reaction

Maeda

Taketsugu

Morokuma

2013

Zeitschrift für Physikalische Chemie

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The present study demonstrates a priori prediction of the mechanism of Paternò-Büchi (PB) reaction by automated search for reaction pathways using the artificial force induced reaction (AFIR) method, for the simplest set of reactants, H 2 CO + C 2 H 4 . The search found all previously suggested pathways automatically without using any guess about the reaction mechanism. Even the reaction product was not assumed. In addition, a comprehensive view of the reaction path network obtained in the present extensive search gave new insights into the mechanism. Barriers on excited states explained the preference of the initial bonding sites. A seam of crossing between the lowest triplet and first singlet excited state is suggested to make a significant contribution to an intersystem crossing and the reaction mechanism of the present system.

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Section: -Msxsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Exploring Pathways of Photoaddition Reactions by Artificial Force Induced Reaction Method: A Case Study on the Paternò–Büchi Reaction

Maeda

Taketsugu

Morokuma

2013

Zeitschrift für Physikalische Chemie

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“…The UV photophysics of benzaldehyde has been investigated extensively; 27-30 the consensus view is that initial photoexcitation to the first excited singlet (S1) state leads to rapid (~100 fs timescale) intersystem crossing (ISC) to either (or both of) the first (T1) or second (T2) triplet excited states. 29 Neither relating to PB reactions [6][7][8][9][10][11][12][13][14][15][16][17]19 suggests that these absorptions are signatures of the biradical intermediate(s) formed by reaction between benzaldehyde(T1) and cyclohexene. Once formed, this biradical would be expected to either undergo intersystem crossing prior to ring-closure (to form the final oxetane), or dissociation to reform benzaldehyde in its S0 state, it is not clear from these measurements whether ISC occurs before or after dissociation has occurred.…”

Section: Resultsmentioning

confidence: 99%

“…An earlier picosecond pump-probe study of the PB reaction of benzophenone and dioxene confirmed the step-wise nature of the reaction by observation of the biradical intermediate created by CC bond formation. 9,19 The nanosecond lifetime of this intermediate was also noted and used to identify that a triplet state biradical had been formed which subsequently underwent intersystem crossing to form the final singlet oxetane product. The reaction now finds widespread use in synthetic chemistry as a means of adding high-level functionality in one preparative step.…”

Section: Introductionmentioning

confidence: 99%

Tracking a Paternò–Büchi Reaction in Real Time Using Transient Electronic and Vibrational Spectroscopies

et al. 2014

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“…Thus, for the triplet, the reaction path can be predicted by the most stable biradical rule [5]. The biradical intermediate in the reaction between benzophenone and electron-rich alkenes has been determined by using laser flash photolysis [6,7]. A conformational analysis of the biradicals has been published [8].…”

Section: Introductionmentioning

confidence: 99%

Regio- and stereoselectivity in the Paternò–Büchi reaction on furan derivatives

D’Auria

Emanuele

Racioppi

2004

Journal of Photochemistry and Photobiology A: Chemistry

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The photochemical coupling reaction between 2,3-dihydrofuran and benzaldehyde was studied by using DFT/B3LYP/6 − 31G + (d, p) method. The regiocontrol of the attack of the benzaldehyde on the double bond is related to the different stabilities of the biradical intermediates. The endo stereoselectivity of the reaction depends on the superposition between HSOMO and LSOMO in the biradical intermediate. In the photochemical reaction between furan and benzaldehyde also the regiocontrol depends on the relative stability of the possible biradical intermediates. The exo stereoselectivity of the coupling reaction depends on the superposition between the HSOMO and LSOMO of the biradical intermediate. The reaction of chiral phenylglyoxylates with furan gave the corresponding adducts with de = 15-95%. The stereocontrol can be explained considering the energy gap between the biradical intermediates in the coupling reaction. When the reaction was performed in the presence of zeolite, the diastereoisomeric excess increased. The reaction of benzoin and 2-phenylpropiophenone with furan gave the cycloadduct with high diastereocontrol. All the products were obtained with de > 98%. The Paterrnò-Büchi reaction between 2-furylmethanols with aromatic carbonyl compounds also showed high regio-and stereocontrol. On the contrary, when 5-methyl derivatives were used, a lack of regiocontrol was observed. Furthermore, with aliphatic carbonyl compounds, no diastereoselectivity was observed. These results were explained assuming the attack of the excited carbonyl compound on the same side as the hydroxyl group, through the formation of a hydrogen bond or of a complex. This type of attack gave the biradical intermediate in preferential conformations. The relative energies of these conformers account for the observed diastereoselectivity.

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Observation of the 1,4 biradical in the Paterno-Buchi reaction

Cited by 103 publications

References 0 publications

Exploring Pathways of Photoaddition Reactions by Artificial Force Induced Reaction Method: A Case Study on the Paternò–Büchi Reaction

Exploring Pathways of Photoaddition Reactions by Artificial Force Induced Reaction Method: A Case Study on the Paternò–Büchi Reaction

Tracking a Paternò–Büchi Reaction in Real Time Using Transient Electronic and Vibrational Spectroscopies

Regio- and stereoselectivity in the Paternò–Büchi reaction on furan derivatives

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