Aldehyde N,N-Dialkylhydrazones as Neutral Acyl Anion Equivalents: Umpolung of the Imine Reactivity

Cycloaddition reactions have figured prominently in both synthetic and mechanistic organic chemistry.1,2 Current understanding of the underlying principles in this area has grown from a fruitful interplay between theory and experiment.3 The monumental work of Huisgen and coworkers in the early 1960s led to the general concept of 1,3-dipolar cycloaddition.4–7 Few reactions rival this process in the number of bonds that undergo transformation during the reaction, producing products considerably more complex than the reactants. Over the years this reaction has developed into a generally useful method of five-membered heterocyclic ring synthesis, since many 1,3-dipolar species are readily available and react with a wide variety of dipolarophiles. 1,3-Dipolar cycloadditions are bimolecular in nature and involve the addition of a 1,3-dipole (1) to a multiple π-bond system (2) leading to five-membered heterocycles (3; equation 1).

4.9 – Intermolecular 1,3-Dipolar Cycloadditions

Catalytic asymmetric intramolecular [3 + 2] cycloaddition of hydrazone/olefins has been attained. In the presence of a chiral zirconium catalyst prepared from zirconium alkoxide and a BINOL derivative, the desired pyrazolidine derivatives were obtained in high yields with high selectivities. The products were easily converted to 1,3-diamine or beta-aminonitrile derivatives by N-N bond cleavage.

Asymmetric intramolecular [3 + 2] cycloaddition reactions of acylhydrazones/olefins using a chiral zirconium catalyst

Asymmetric Brønsted acid catalyzed cycloadditions--efficient enantioselective synthesis of pyrazolidines, pyrazolines, and 1,3-diamines from N-acyl hyrazones and alkenes.

This paper discusses a novel approach that may provide a complete solution to combating oil spills. The technology is centered on a cross-linked polyolefin terpolymer (x–OS–DVB), containing 1-octene, styrene, and divinylbenzene units, which is an oil superabsorbent polymer (oil–SAP) with aliphatic and aromatic side chains that have similar solubility parameters (oleophilic and hydrophobic properties), with the hydrocarbons in crude oil. Some x–OS–DVB terpolymers, with desirable morphology (amorphous, low Tg, and high free volume) and lightly cross-linked (complete network) structure, show rapid oil absorption and swelling to reach a capacity 45 times their weight. The capacity of oil uptake (swelling) is inversely proportional to the cross-linking density. The combination of selective oil absorption (without water) and tough mechanical strength offers buoyancy, stability, and easy recovery on water surfaces. The recovered oil-swelled gel, containing more than 98% oil and 2% x–OS–DVB, is suitable for regul...

Novel Solution to Oil Spill Recovery: Using Thermodegradable Polyolefin Oil Superabsorbent Polymer (Oil–SAP)

Cycloadditions intramoleculaires cationique 3+ + 2 et dipolaire-1,3 de phenylhydrazones.

Reactivite des imines vis a vis d'alcenes gem disubstitues : Synthese d'aza-1 bicyclo (2,1,0) pentanes

Mineral oil diffusion in styrene-butadiene polymer films was investigated with a simple gravimetric sorption method. Over the selected range of temperatures and film thicknesses for which sorption tests were performed, the diffusion process is described in terms of Fick's third law. Polymer dissolution was found to compete with the diffusion process especially at high temperature. Possible interference due to dissolution on data generated using a gravimetric method, resulted in an estimation of apparent activation energy using diffusion coefficient set calculated with Crank's half-time relationship. The mineral oil diffusion activation energy was found to be relatively high compared with those of hydrocarbons diffusing in natural and synthesized rubbers or crosslinked polybutadiene as reported in the literature. The influence of polymer Tg, crosslinking density, and polarity on mineral oil ability to penetrate polymer film was evaluated in terms of percent weight increase over time. Maximum absorption after 60-min sorption time linearly correlates with mineral oil absorption rate for polymers prepared with different structures. This linear relationship suggests that diffusion of solvent in styrene-butadiene polymers reveals the macroscopic composition and structural polymer modification rather than local changes. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

B. Fouchet

Papers

Cycloadditions intramoleculaires cationique 3+ + 2 et dipolaire-1,3 de phenylhydrazones.

Reactivite des imines vis a vis d'alcenes gem disubstitues : Synthese d'aza-1 bicyclo (2,1,0) pentanes

Diffusion of mineral oil in styrene-butadiene polymer films

L'α-bromoacrylate de methyle, un reactif de bicyclisation en serie heterocyclique : Preparation des aza-1 bicyclo(2,1,0) pentanes.

Réactions de cyclopropanation par double addition de Michael.