Buffered potassium peroxymonosulfate-acetone epoxidation of .alpha.,.beta.-unsaturated acids

Corey, Paul F.; Ward, Frederick E.

doi:10.1021/jo00360a059

Cited by 65 publications

(22 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Signals corresponding to 1 C, 2 C, and 4 C of aliphatic end group were not observed due to the low concentration. 13 C-NMR experiment allowed the assignation of the carbons not attached to hydrogens matching the calculated model.…”

Section: Structural Characterization Of Ptobee-cholinementioning

confidence: 67%

“…The structures of undec-10-enamide, 10-11-epoxy-undecanamide, and 10,11-dihydroxyundecanamide (III, IV and V in Figure 4) were confirmed by 1 H-NMR, 13 C-NMR, registered in DMSO-d 6 at 25°C in a Bruker 300 MHz NMR spectrometer. Chemical shifts and Mass spectrometry results are given in Section 2.3.…”

Section: Structural Characterization Of Ptobume-amidementioning

confidence: 77%

“…Poly[oxy(1,2-undecan-11-amidyl)-oxycarbonyl-1,4-phenylene-oxy-1,4-terephthaloyl-oxy-1,4-phenylene-carbonyl], VII in Figure 4, was obtained through polycondensation reaction between 4 and 4′-(terephthaloyldioxydibenzoic chloride) TOBC and the racemic mixture of DL-10,11-dihydroxyundecanemide (V in Figure 4) [11][12][13][14][15]. Similar notation has been used than with precursor cholesteric liquid crystal PTOBDME, Figure 1.…”

Section: Synthesis Of Cholesteric Ptobume-amide [(C 33 H 33 O 9 N) Nmentioning

confidence: 99%

See 2 more Smart Citations

Synthetic Cationic Cholesteric Liquid Crystal Polymers

Méndez¹

2018

Liquid Crystals - Recent Advancements in Fundamental and Device Technologies

View full text Add to dashboard Cite

We report the synthesis of six multifunctional cationic cholesteric liquid crystals polyesters functionalized with choline, amine, and amide groups to obtain new chemical formulations involving macromolecular features with new properties added to those of precursor chiral cholesteric polyesters. They are designed as PTOBDME-choline [(C 34 H 36 O 8) n ─C 5 H 13 N]; PTOBEE-choline [(C 26 H 20 O 8) n ─C 5 H 13 N]; PTOBDME-ammonium [(C 34 H 36 O 8) n ─C 5 H 13 N]; PTOBEE-ammonium [(C 26 H 20 O 8) n ─C 5 H 13 N]; PTOBUME-amide (C 33 H 33 O 9 N) n ; and PTOBEE-amide (C 26 H 19 O 9 N) n. Structural characterization is performed by NMR. Thermal behavior is studied by thermogravimetry (TG) and differential scanning calorimetry (DSC), showing all the polymers endothermic transition from crystal phase to liquid crystal mesophase. Chirality is determined by optical rotatory dispersion (ORD). The cationic cholesteric liquid crystal polymers described here have proved to act as nonviral vectors in gene therapy, transfecting DNA to the nucleus cell.

show abstract

Section: Structural Characterization Of Ptobee-cholinementioning

confidence: 67%

Section: Structural Characterization Of Ptobume-amidementioning

confidence: 77%

Section: Synthesis Of Cholesteric Ptobume-amide [(C 33 H 33 O 9 N) Nmentioning

confidence: 99%

See 1 more Smart Citation

Synthetic Cationic Cholesteric Liquid Crystal Polymers

Méndez¹

2018

Liquid Crystals - Recent Advancements in Fundamental and Device Technologies

View full text Add to dashboard Cite

show abstract

“…Previously, it was reported that the in situ generated dimethyldioxirane (2 a) is effective for the epoxidation of cinnamic acids and esters 13), while the transformation of phenylpropiolic acid into phenylacetic acid was postulated to proceed through an oxirene intermediate14).…”

mentioning

confidence: 99%

Dioxirane Epoxidation of α,β‐Unsaturated Ketones

1991

View full text Add to dashboard Cite

The synthesis of epoxides 3a -r is achieved in excellent yields by reaction of the a,P-unsaturated ketones l a -c , 4,4'-disubstituted (E)-chalcones 1 d -0 , and 2'-hydroxy-4-substituted (E)-chalcones l p -r with isolated dimethyldioxirane (2a) (as acetone solution) and/or in situ generated ethyl(methy1)dioxirane (2b). This method constitutes a useful alternative to the Weitz-Scheffer epoxidation (alkaline H202) of such electronpoor substrates.Chalcone epoxides are natural products which are commonly formed in plants ') and exhibit important biological activity, e.g. they act as potent inhibitors of the cytosolic epoxide hydrolase'). The synthetic utility of such functionalized epoxides has been unquestionably demonstrated3), a fact that underscores the need of new methods for the convenient and efficient preparation of these valuable "building blocks" in organic synthesis.Two evident methodologies are either Sharpless epoxidation4) of allylic alcohols and subsequent oxidation of the hydroxy functionality, or alternatively direct epoxidation of a$-unsaturated ketones by alkaline hydrogen peroxide and its alkyl and silyl derivatives (Weitz-Scheffer reaction5)). For base-sensitive functional groups, e. g. phenolic substituents, undesirable oxidations of the aromatic moiety may become prominent. The use of electrophilic oxidants such as peracids are frequently complicated by the facile Baeyer-Villiger rearrangement 6, of such electron-poor substrates. The basecatalyzed dehydrohalogenation of halohydrin may provide a useful entry into chalcone epoxides7), but the preparation of the halohydrin precursors from the chalcones is not compatible with a number of functionalities.Dimethyldioxirane (2a) is a selective and powerful oxygen transfer agent *I, that besides its high propensity to epoxidize electron-rich double bonds, has recently been shown to work well in its isolated form as acetone solution9) with disubstituted a$-unsaturated acids and esters"), p-0x0 enol ethers 'I), and even the labile a-methy1ene-P-lactonesl2) (Scheme 1). Previously, it was reported that the in situ generated dimethyldioxirane (2 a) is effective for the epoxidation of cinnamic acids and esters 13), while the transformation of phenylpropiolic acid into phenylacetic acid was postulated to proceed through an oxirene intermediate14).In view of the convenience and efficiency of dimethyldioxirane (2a) as oxidant*), we decided to test it in the direct conversion of a$-unsaturated ketones into their epoxides. * ) Undergraduate Research Participant, University of Wurzburg, Spring 1990. In this paper we describe our results obtained by using isolated dimethyldioxirane (2a) (as acetone solution) and our new in situ method, which utilizes ethyl(methy1)dioxirane (2b) prepared from 2-butanone and Caroate.Scheme 1. Previous epoxidations of u,P-unsaturated carbonyl derivatives by dimethyldioxirane R R Results and DiscussionThe a$-unsaturated ketones 1 a -r are transformed by isolated dimethyldioxirane (2a) (as acetone solution) into the corresponding ep...

show abstract

“…Dimethyldioxirane (2a) is a selective and powerful oxygen transfer agent *I, that besides its high propensity to epoxidize electron-rich double bonds, has recently been shown to work well in its isolated form as acetone solution9) with disubstituted a$-unsaturated acids and esters"), p-0x0 enol ethers 'I), and even the labile a-methy1ene-P-lactonesl2) (Scheme 1). Previously, it was reported that the in situ generated dimethyldioxirane (2 a) is effective for the epoxidation of cinnamic acids and esters 13), while the transformation of phenylpropiolic acid into phenylacetic acid was postulated to proceed through an oxirene intermediate14).…”

mentioning

confidence: 99%