Stabilization and activation of unstable propynal in the zeolite nanospace and its application to addition reactions

We investigated in detail how polar cumulene molecules like diphenylketene were accommodated in faujasite zeolite pores based on 13C CP/MAS and DD/MAS NMR analyses as well as quantum chemical calculations after adsorbing the molecule into the zeolite NaY or AgY having “hard” sodium ions or “soft” silver ions. Since the diphenylketene has such a specific structure that a carbonyl group (a hard base) is accumulated by a carbon-carbon double bond (a soft π base), which is conjugated with two benzene rings (soft π bases), it is possible for the diphenylketene to adopt multicoordination modes to different metal ions in the zeolite. Compared with the coordination modes of benzophenone and 1,1-diphenylethene adsorbed in the NaY and AgY, those of diphenylketene were identified, and specific coordination behaviors in the zeolite’s supercages were classified depending on the hard or soft metal characters: The C=O and phenyl coordination modes to Na+ in NaY prevail, while the C=C and phenyl coordination to Ag+ in AgY is favored. We also unveiled the difference in the molecular mobility depending on the types of cations in the zeolite by comparing the 13C CP/MAS and DD/MAS NMR spectra.

show abstract

Coordination Behaviors of Diphenylketene Adsorbed in the Nanocages of Zeolite NaY and AgY

Shibata

Masui

Onaka

2020

Bulletin of the Chemical Society of Japan

View full text Add to dashboard Cite

show abstract

Synthesis of N-Unprotected Diaryl Ketimines and Alkyl Ketimines from Ketones and Ammonia Using Porous Solid Acids with Analysis of Their Adsorption Behavior

Shibata,

Masui,

Narukawa

et al. 2023

Bulletin of the Chemical Society of Japan

View full text Add to dashboard Cite

The most atom-efficient synthetic method for N-unprotected ketimines (N-H ketimines) from ketones is the dehydration condensation reaction with ammonia (NH3). However, until now, few synthetic methods for N-H ketimines with high versatility have been known. In this study, we examined various solid acids and found that N-H diaryl ketimines with various functional groups on the aryl groups could be synthesized in high yields from diaryl ketones and NH3 under solvent-free conditions using silica-alumina (SiO2-Al2O3) or proton-exchanged Y-type zeolite (H-Y). Solid-state 13C and 15N NMR measurements indicated that the N-H ketimine formed in the pores of acidic zeolite was coordinated to NH4+ species on the pore surface. By quantum chemical calculations we also discussed the reason why the dehydration-condensation reaction between ketone and NH3, which is an endothermic reaction in a vacuum, was biased toward the product side in the actual experiment. In addition, this synthetic method can be applied to synthesize N-H alkyl ketimines with α-acidic hydrogens, which are less stable and more sensitive to hydrolysis and oligomerization than diaryl ketimines.

show abstract

A Scope of Chiral Cyclopropanations of Various α-functionalized Diazoketone Derivatives with Styrene Catalyzed by p-Nitro Ru(II)-diphenyl- Pheox Complex

Loan

Iwasa

2023

LOC

View full text Add to dashboard Cite

show abstract

scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.

Contact Info

hi@scite.ai

10624 S. Eastern Ave., Ste. A-614

Henderson, NV 89052, USA

Blog Terms and Conditions API Terms Privacy Policy Contact Cookie Preferences Do Not Sell or Share My Personal Information

Made with 💙 for researchers

Part of the Research Solutions Family.

Stabilization and activation of unstable propynal in the zeolite nanospace and its application to addition reactions

Abstract: Propynal is stabilized in the Na-Y zeolite at ambient temperature and simultaneously activated to form pyrazoles, cinnamaldehydes, and cyclobutenes.

Cited by 3 publications

References 43 publications

Coordination Behaviors of Diphenylketene Adsorbed in the Nanocages of Zeolite NaY and AgY

Coordination Behaviors of Diphenylketene Adsorbed in the Nanocages of Zeolite NaY and AgY

Synthesis of N-Unprotected Diaryl Ketimines and Alkyl Ketimines from Ketones and Ammonia Using Porous Solid Acids with Analysis of Their Adsorption Behavior

A Scope of Chiral Cyclopropanations of Various α-functionalized Diazoketone Derivatives with Styrene Catalyzed by p-Nitro Ru(II)-diphenyl- Pheox Complex

Contact Info

Product

Resources

About