Boosted molecular mobility during common chemical reactions

Science ◽  
2020 ◽  
Vol 369 (6503) ◽  
pp. 537-541 ◽  
Author(s):  
Huan Wang ◽  
Myeonggon Park ◽  
Ruoyu Dong ◽  
Junyoung Kim ◽  
Yoon-Kyoung Cho ◽  
...  
Keyword(s):  
Chemical Reactions ◽  
Alder Reaction ◽  
Diels Alder ◽  
Brownian Diffusion ◽  
Organic Chemical ◽  
Sonogashira Coupling ◽  
Substitution Reactions ◽  
Bimolecular Reactions ◽  
Diels Alder Reaction ◽  
Instrumental Resolution

Mobility of reactants and nearby solvent is more rapid than Brownian diffusion during several common chemical reactions when the energy release rate exceeds a threshold. Screening a family of 15 organic chemical reactions, we demonstrate the largest boost for catalyzed bimolecular reactions, click chemistry, ring-opening metathesis polymerization, and Sonogashira coupling. Boosted diffusion is also observed but to lesser extent for the uncatalyzed Diels-Alder reaction, but not for substitution reactions SN1 and SN2 within instrumental resolution. Diffusion coefficient increases as measured by pulsed-field gradient nuclear magnetic resonance, whereas in microfluidics experiments, molecules in reaction gradients migrate “uphill” in the direction of lesser diffusivity. This microscopic consumption of energy by chemical reactions transduced into mechanical motion presents a form of active matter.

Synthesis of highly functionalized naphthoate precursors to damavaricin D — Observation of kinetically stable benzocyclohexadienones in the bromination reactions of highly functionalized β-naphthol derivatives

2001 ◽  
Vol 79 (11) ◽  
pp. 1711-1726
Author(s):  
William R Roush ◽  
David J Madar ◽  
D Scott Coffey
Keyword(s):  
Total Synthesis ◽  
Chloride Ion ◽  
Alder Reaction ◽  
Diels Alder ◽  
Substitution Reactions ◽  
Diels Alder Reaction ◽  
Reaction Proceeds ◽  
Bromide Ion ◽  
Aromatic Bromination ◽  
Naphthol Derivatives

Selective syntheses of the highly substituted bromonaphthoates 4a, 4b, 19, and 22 are reported. These compounds were targeted as precursors to the naphthoquinone nucleus of damavaricin D; compound 22 ultimately was used in the successful total synthesis. The synthesis of 22 features the Diels–Alder reaction of the oxygenated diene 5 and 2,6-dibromo-3-methylbenzoquinone 6 to establish the core naphthalenic unit. The quinone was protected throughout this synthesis as a 1,4-bis-methoxymethyl-1,4-dihydroquinone (see 36). The C-2-carboalkoxy group of 22 was added by carboxylation of the aryllithium intermediate generated from 36, and protected as a β-trimethylsilylethyl ester. Finally, the C-8-Br substituent was introduced by NBS bromination of 38. This reaction proceeds by way of bromobenzocyclohexadienone 39. Related bromobenzo-cyclohexadienones 13 and 29 were observed in the NBS brominations of the highly functionalized β-naphthyl MOM ethers 11 and 28. The bromobenzocyclohexadienones 29 and 39 undergo facile substitution reactions with chloride ion and reduction with bromide ion at rates competitive with base-promoted aromatization. The surprising kinetic stability of these intermediates is attributed to a combination of steric and stereoelectronic factors.Key words: damavaricin D, naphthoate precursors, kinetically stable benzocyclohexadienones, aromatic bromination.

Organic reactions in liquid crystalline solvents. 2. An investigation into the use of liquid crystalline solvents to effect stereochemical control in the Diels–Alder reaction

1985 ◽  
Vol 63 (10) ◽  
pp. 2736-2741 ◽  
Author(s):  
William J. Leigh
Keyword(s):  
Liquid Crystalline ◽  
Transition States ◽  
Alder Reaction ◽  
Diels Alder ◽  
Shape Transition ◽  
Bimolecular Reactions ◽  
Solvent Phase ◽  
Stereochemical Control ◽  
Diels Alder Reaction ◽  
Liquid Crystalline Phases

The possibility of using liquid crystalline solvents to control the stereospecificity of bimolecular reactions as a result of differences in liquid crystalline solvation of the various possible transition states has been examined. The Diels–Alder reactions of 2,5-dimethyl-3,4-diphenylcyclopentadienone with four dienophiles of varying steric size (cyclopentene, cycloheptene, indene, and acenaphthylene) have been carried out in benzene, cholesteryl nonanoate (isotropic), cholesteryl propionate (cholesteric), and 4-ethyl-4′-(4-pentylcyclohexyl)biphenyl (smectic) at 105 °C. In spite of very large differences in steric solvation requirements for the endo- (globular in shape) and exo- (plate-like in shape) transition states in these reactions, no variation in product ratio with solvent phase is observed in any case.The inability of the ordered liquid crystalline phases to differentiate between endo- and exo-transition states in the Diels–Alder reactions investigated is rationalized as being the possible result of several factors. The most important of these are believed to be free volume effects, owing to both inefficient steric solvation of the bulky diene and volume contraction in the transition states for cycloaddition.

scholarly journals Diels–Alder reactions and electrophilic substitutions with atypical regioselectivity enable functionalization of terminal rings of anthracene

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Vinh Ngoc Huynh ◽  
Michael Leitner ◽  
Aditya Bhattacharyya ◽  
Lisa Uhlstein ◽  
Peter Kreitmeier ◽  
...  
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Substitution Reactions ◽  
Central Ring ◽  
Synthetic Strategy ◽  
Diels Alder Reaction ◽  
Formidable Challenge ◽  
Highest Occupied Molecular Orbital ◽  
Regioselective Functionalization ◽  
Aromatic Stabilization

Abstract Reversing the regioselectivity of the renowned Diels–Alder reaction by overriding the usual thermodynamic and kinetic governing factors has always been a formidable challenge to synthetic organic chemists. Anthracenes are well-known to undergo [4 + 2]-cycloadditions with dienophiles at their 9,10-positions (central ring) over 1,4-positions (terminal ring) guided by the relative aromatic stabilization energy of the two possible products, and also by harboring the largest orbital coefficients of the highest occupied molecular orbital (HOMO) at the 9,10-positions. We, herein, report a 1,4-selective [4 + 2]-cycloaddition strategy of 9,10-unsubstituted anthracenes by installing electron-donating substituents on the terminal rings which is heretofore unprecedented to the best of our knowledge. The developed synthetic strategy does not require any premeditated engagement of the 9,10-positions either with any sterically bulky or electron-withdrawing substituents and allows delicate calibration of the regioselectivity by modulating the electron-donating strength of the substituents on the terminal rings. Likewise, the regioselective functionalization of the terminal anthracene ring in electrophilic substitution reactions is demonstrated. A mechanistic rationale is offered with the aid of detailed computational studies, and finally, synthetic applications are presented.

Synthesis of myxobacteria metabolites

2012 ◽  
Vol 84 (6) ◽  
pp. 1421-1433 ◽  
Author(s):  
Stephen L. Birkett ◽  
Darran A. Loits ◽  
Samantha Wimala ◽  
Mark A. Rizzacasa
Keyword(s):  
Total Synthesis ◽  
Biological Activities ◽  
Aldol Reaction ◽  
Alder Reaction ◽  
Diels Alder ◽  
Sonogashira Coupling ◽  
Partial Reduction ◽  
Diels Alder Reaction ◽  
Apicularen A ◽  
Excellent Source

Myxobacteria are an excellent source of novel secondary metabolites with a range of biological activities. This review details the synthesis of several examples of these natural products. The total synthesis of all the members of the crocacin family is presented where the stereochemistry of the stereotetrad was set via a tin-mediated syn-aldol reaction followed by selective anti-reduction. The other key step in the route to crocacins A, B, and D was the introduction of the enamide functionality by acylation of an enecarbamate. A formal synthesis of apicularen A is also discussed, which involved a base-induced macrolactonization reaction and a transannular oxy-Michael cyclization to secure the tetrahydropyran ring. Finally, the total synthesis of deshydroxyajudazol B is summarized. This route details a modified approach to the 2,4-disubstituted oxazole, and a Diels–Alder reaction followed by aromatization was utilized to form the isochromanone moiety. A highly efficient Sonogashira coupling followed by partial reduction then gave deshydroxyajudazol B.

Effect of solvent motions on the dynamics of the Diels-Alder reaction

2021 ◽  
Author(s):  
Xiaoyong Zhang ◽  
Pierre-louis Lefebvre ◽  
Jeremy Harvey
Keyword(s):  
Chemical Reactions ◽  
Shape Change ◽  
Alder Reaction ◽  
Diels Alder ◽  
Effect Of Solvent ◽  
Diels Alder Reaction

How solvent motions affects the dynamics of chemical reactions in which the solute undergoes a substantial shape change is a fundamental but elusive issue. This work utilizes reactive simulation and...

The Diels-Alder Reaction of 2-Ethenyl-1,4-Benzodioxin: A New and Simple Synthesis of Bisaryl Ethers

Synlett ◽  
1989 ◽  
Vol 1989 (01) ◽  
pp. 30-32
Author(s):  
Thomas V. Lee ◽  
Alistair J. Leigh ◽  
Christopher B. Chapleo
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Simple Synthesis ◽  
Diels Alder Reaction

The intermolecular anthracene-transfer in a regiospecific antipodal C60 difunctionalization

2020 ◽  
Author(s):  
Radu Talmazan ◽  
Klaus R. Liedl ◽  
Bernhard Kräutler ◽  
Maren Podewitz
Keyword(s):  
Noncovalent Interactions ◽  
Interaction Model ◽  
Alder Reaction ◽  
Diels Alder ◽  
Stacking Interactions ◽  
Pi Stacking ◽  
Diels Alder Reaction ◽  
Double Decker ◽  
Anthracene Molecule ◽  
New Strategies

We analyze the mechanism of the topochemically controlled difunctionalization of C60 and anthracene, where an anthracene molecule is transferred from one C60 monoadduct to another one under exclusive formation of equal amounts of C60 and the difficult to make antipodal C60 bisadduct. Our herein disclosed dispersion corrected DFT studies show the anthracene transfer to take place in a synchronous retro Diels-Alder/Diels-Alder reaction: an anthracene molecule dissociates from one fullerene under formation of an intermediate, while already undergoing stabilizing interactions with both neighboring fullerenes, facilitating the reaction kinetically. In the intermediate, a planar anthracene molecule is sandwiched between two neighboring fullerenes and forms equally strong "double-decker" type pi-pi stacking interactions with both of these fullerenes. Analysis with the distorsion interaction model shows that the anthracene unit of the intermediate is almost planar with minimal distorsions. This analysis sheds light on the existence of noncovalent interactions engaging both faces of a planar polyunsaturated ring and two convex fullerene surfaces in an unprecedented 'inverted sandwich' structure. Hence, it sheds light on new strategies to design functional fullerene based materials.<br>

Sign in / Sign up

Export Citation Format

Share Document