Abstract:We report the observation of changes in the wave turbulence properties of gravitycapillary surface waves due to a finite-depth effect. When the fluid depth is decreased, a hump is observed on the wave spectrum in the capillary regime at a scale that depends on the depth. The possible origin of this hump is discussed. In the gravity regime, the wave spectrum still shows a power law but with an exponent that strongly depends on the depth. A change in the scaling of the gravity spectrum with the mean injected pow… Show more
“…Similarly, conjugate dienes are valuable products or intermediates in organic chemistry 11. Although numerous methods are available to prepare di‐ or trisubstituted dienes, effective methods to prepare more highly substituted dienes are limited 12…”
Unlike the widely studied linear diaryliodoniums as electrophilic arylating reagents, cyclic diaryliodoniums have the potential to initiate dual arylations with atom and step economy. In our current work, cascade reactions of cyclic diaryliodoniums and two equivalent alkynes have been successfully achieved under mild conditions, catalyzed by CuI/PdCl2(PPh3)2. The transformation could also be realized in a stepwise way with two different alkynes or with one alkyne and one alkene. The reaction enables a rapid access to a variety of complex fluorenes containing conjugate enyne and diene fragments.
“…Similarly, conjugate dienes are valuable products or intermediates in organic chemistry 11. Although numerous methods are available to prepare di‐ or trisubstituted dienes, effective methods to prepare more highly substituted dienes are limited 12…”
Unlike the widely studied linear diaryliodoniums as electrophilic arylating reagents, cyclic diaryliodoniums have the potential to initiate dual arylations with atom and step economy. In our current work, cascade reactions of cyclic diaryliodoniums and two equivalent alkynes have been successfully achieved under mild conditions, catalyzed by CuI/PdCl2(PPh3)2. The transformation could also be realized in a stepwise way with two different alkynes or with one alkyne and one alkene. The reaction enables a rapid access to a variety of complex fluorenes containing conjugate enyne and diene fragments.
“…Substituted 1,3-dienes are common synthetic building blocks featured in a wide array of complexity-building catalytic transformations, including recently developed asymmetric hydrofunctionalizations, 1 difunctionalizations, 2 C−H functionalizations, 3 cycloadditions, 4 and cross-coupling. 5 Preparations of 1,3-dienes, 1-aryl-1,3-dienes being a particularly prevalent subset in modern catalytic methods, classically involve disconnections at the central sigma bond of the diene, 6 such as through Mizoroki-Heck reactions, cross-coupling, 7,8 and ene-yne metathesis, 9 or disconnection at the double bond in the case of Wittig-type olefinations (Scheme 1, left). 10 Drawbacks of these approaches include functional group compatibility with strongly basic organometallic reagents or, more importantly, limited structural diversity in commercial starting materials (i.e., styrenyl halides or cinnamaldehydes).…”
Substituted 1,3-dienes are valuable synthetic intermediates used in myriad catalytic transformations, yet modern catalytic methods for their preparation in a highly modular fashion using simple precursors are relatively few. We report here an aerobic boron Heck reaction with cyclobutene that forms exclusively linear 1-aryl-1,3-dienes using (hetero)arylboronic acids, or 1,3,5-trienes using alkenylboronic acids, rather than typical Heck products (i.e., substituted cyclobutenes). Experimental and computational mechanistic data support a pericyclic mechanism for C−C bond cleavage that enables the cycloalkene to circumvent established limitations associated with diene reagents in Heck-type reactions.
“…The structures of all synthesized dienes 3, including the configurational assignment and the location of the substituents, were unambiguously proven by 1 H, 13 C, and 2D (NO-ESY, 1 H-13 C HSQC, 1 H-13 C HMBC) NMR spectroscopy. For example, in the 2D NOESY spectra of 3aa (Figure 1), crosspeaks were observed between the signals of proton at the C 1′ and protons at the ortho-position of the benzoyl moiety for E,E-isomer of 3aa, while for Z,E-isomer of 3aa crosspeaks between the signals of proton at the C 1′ and protons at the C 3 and C 4 were detected.…”
2-Acylbuta-1,3-dienes have been synthesized regioselectively from aromatic and heteroaromatic β,γ-unsaturated ketones (readily accessible via base-catalyzed addition of ketones to acetylenes) and aldehydes. The reaction smoothly proceeds with piperidine (10 mol%)/acetic acid (10 mol%) catalytic pair in boiling toluene to provide synthetically attractive polyconjugated electron-deficient dienes in up to 94% yield.
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