Intramolecular Cycloaddition Reactions of ω-Unsaturated Chiral Nitrones

Marcus, Jan; Brussee, Johannes; Gen, A. Van Der

doi:10.1002/(sici)1099-0690(199811)1998:11<2513::aid-ejoc2513>3.0.co;2-u

Cited by 21 publications

(5 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Synthesis of the Monomers. For the synthesis of the chiral dopant 1 (see Scheme 1), chiral induction was achieved by enzymatically catalyzed 26 asymmetric addition of HCN to the aldehyde group of pent-1-en-5-al 2 which lead to the chiral cyanohydrine 3. For the rigid core, p-hydroxycarboxylic methyl carboxylate 4 and hex-1-en-6-ol were linked by a Mitsunobu etherification.…”

Section: Methodsmentioning

confidence: 99%

Shear Deformation and Ferroelectricity in Chiral SmC* Main-chain Elastomers

Heinze

Finkelmann

2010

Macromolecules

View full text Add to dashboard Cite

Ferroelectric smectic main-chain liquid crystalline elastomers were synthesized and subjected to simple shear deformation to achieve reorientation of the layer structure and the formation of a macroscopic spontaneous polarization. The phase behavior and structural parameters of these elastomers are investigated and discussed. A shear-induced splitting of the X-ray scattering intensity distribution is found. A splitting of the sample in domains of two director orientations that couple differently to the shear deformation is proposed. The smectic layers also move at different affinities depending on their initial orientation. The smectic layer spacing was found to be nearly constant even though the smectic tilt angle changes significantly. The realignment of the smectic layers indicates a migration process, where depending on their original orientation the layer normals are leaving or entering the X-ray scattering plane. The spontaneous polarization was found to be linearly dependent on the dopant concentration with Ps = 30 nC/cm 2 for a system doped with 11 wt % of chiral dopant.

show abstract

Section: Methodsmentioning

confidence: 99%

Shear Deformation and Ferroelectricity in Chiral SmC* Main-chain Elastomers

Heinze

Finkelmann

2010

Macromolecules

View full text Add to dashboard Cite

show abstract

“…Upon applying the usual reduction conditions (Zn/AcOH) for cleaving the isoxazolidine ring of 11b and 11c, 21 pyrrolizines 12a,b, respectively, were obtained in high yields (Scheme 2).…”

Section: Methodsmentioning

confidence: 99%

2-Formylpyrroles as Building Blocks in a Divergent Synthesis of Pyrrolizines

et al. 2016

View full text Add to dashboard Cite

The selective functionalization of 2-formylpyrrole to provide diverse 1,2-and 1,2,5-substituted pyrroles is described. These compounds were used as versatile building blocks in a divergent synthesis of biologically valuable aza-bycyclic skeletons, such as pyrrolizine and pyrrolizidine derivatives. These bicycles were prepared following metalfree cascade synthetic approaches via regioselective intramolecular 1,3dipolar cycloadditions and stereoselective Knoevenagel/Michael/ cyclization with dimethyl malonate.

show abstract

“…210 Intramolecular cycloaddition of chiral nitrone 382 followed by reductive opening of the isoxazolidine ring, gives highly functionalised cycloheptanols 383 in high enantiomeric purity by a two-step process (Scheme 165). 211 A novel and general route to pseudoguaianolide sesquiterpenoids employs a diastereoselective 7-endo-trig acyl radical cyclisation of phenylselenyl ketone 384 to give bicycle 385 in 85% yield as the only product (Scheme 166). 212 cations is also a high yielding process (Scheme 111, DCN = 1,4dicyanonaphthalene).…”

Section: Cyclisations Forming One Endocyclic Bond and Rearrangementsmentioning

confidence: 99%