scholarly journals Photochemical Ring-Opening and Intramolecular Hydrogen Shift Reactions in Sulfur Analogues of α-Pyrone

2006 ◽  
Vol 110 (20) ◽  
pp. 6415-6425 ◽  
Author(s):  
S. Breda ◽  
I. Reva ◽  
L. Lapinski ◽  
M. L. S. Cristiano ◽  
L. Frija ◽  
...  
Keyword(s):  
Ring Opening ◽  
Hydrogen Shift ◽  
Intramolecular Hydrogen

The atmospheric oxidation of dimethyl, diethyl, and diisopropyl ethers. The role of the intramolecular hydrogen shift in peroxy radicals

2016 ◽  
Vol 18 (11) ◽  
pp. 7707-7714 ◽  
Author(s):  
Sainan Wang ◽  
Liming Wang
Keyword(s):  
Atmospheric Oxidation ◽  
Peroxy Radicals ◽  
Hydrogen Shift ◽  
Intramolecular Hydrogen ◽  
Clean Atmosphere

Ethers can be auto-oxidized with no O3 formation in a ‘clean’ atmosphere.

scholarly journals Stereoselective Ammonium-Directed Epoxidation in the Asymmetric Syntheses of Dihydroconduramines (–)-A-2, (–)-B-2, (–)-C-3 and (+)-F-3

Synthesis ◽  
2017 ◽  
Vol 50 (01) ◽  
pp. 64-83 ◽  
Author(s):  
Stephen Davies ◽  
Solange Da Silva Pinto ◽  
Ai Fletcher ◽  
Paul Roberts ◽  
James Thomson
Keyword(s):  
Hydrogen Bond ◽  
Intramolecular Hydrogen Bond ◽  
Ring Opening ◽  
Asymmetric Syntheses ◽  
Directing Group ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bond Donors

Epoxidation of racemic trans-2-(N,N-dibenzylamino)cyclohex-3-en-1-ol, upon treatment with Cl3CCO2H then m-CPBA, proceeded with poor diastereoselectivity (ca. 60:40 dr), whilst epoxidation of racemic trans-2-(N-benzylamino)cyclohex-3-en-1-ol under the same conditions proceeded with high diastereoselectivity (>95:5 dr) and was followed by completely regioselective and stereospecific ring-opening in situ to give, after methanolysis of the intermediate trichloroacetate ester, (1RS,2SR,3SR,4SR)-2-(N-benzylamino)cyclohexane-1,3,4-triol. Use of aq HBF4 as the acid protecting agent gave the amino triol directly. The differing diastereoselectivities of these epoxidation reactions may be due to a predilection towards formation of an intramolecular hydrogen-bond in the former substrate disrupting the ability of the in situ formed ammonium moiety to act as a directing group for the incoming oxidant; the presence of two potential hydrogen-bond donors (i.e., two N–H bonds) in the latter substrate circumvents this limitation. With the criterion for a highly diastereoselective (ammonium-directed) epoxidation in this system established, a synthesis of enantiopure trans-2-(N-benzylamino)cyclohex-3-en-1-ol (>99% ee) was developed and the ammonium-directed epoxidation was then employed as a key synthetic step to facilitate the asymmetric syntheses of enantiopure dihydroconduramines (–)-A-2, (–)-B-2, (–)-C-3 and (+)-F-3 (>98% ee in each case) from 1,3-cyclohexadiene.

Thermal rearrangement of 5,6,6-triphenylbicyclo[3.1.0]hex-2-ene to 6,7-benzo-1,5-diphenyltricyclo[3.2.1.02,8]octane

1980 ◽  
Vol 58 (3) ◽  
pp. 210-213 ◽  
Author(s):  
Stefan Weigl ◽  
John Warkentin
Keyword(s):  
Ring Opening ◽  
The Other ◽  
Thermal Rearrangement ◽  
Initial Formation ◽  
Hydrogen Shift ◽  
Benzene Rings ◽  
Shielding Properties

The triphenyl vinylcyclopropane system, 5,6,6-triphenylbicyclo[3.1.0]hex-2-ene, 1, undergoes clean thermal rearrangement, at 210 °C, to 6,7-benzo-1,4-diphenyltricyclo[3.2.1.02,8]octane, 9. This result indicates that 1 behaves like a phenylcyclopropane and not like a vinylcyclopropane in the thermal ring opening. The proposed mechanism involves initial formation of a 1,3-diradical, one site of which is benzyl as well as homoallyl and the other site of which is both benzhydryl and homoallyl. Subsequent steps involve coupling of the radical sites through one of the phenyl groups and a suprafacial 1,5-hydrogen shift concerted with generation of a new cyclopropane ring.The 1Hmr and 13Cmr spectra of 9 are reported and discussed in terms of the shielding properties of cyclopropane and benzene rings.

A Computational Kinetics Study on the Intramolecular Hydrogen Shift Reactions of Alkylperoxy Radicals in 2-Methyltetrahydrofuran Oxidation

2017 ◽  
Vol 49 (6) ◽  
pp. 419-437 ◽  
Author(s):  
Prajakta R. Parab ◽  
Naoki Sakade ◽  
Yasuyuki Sakai ◽  
Ravi Fernandes ◽  
K. Alexander Heufer
Keyword(s):  
Kinetics Study ◽  
Hydrogen Shift ◽  
Intramolecular Hydrogen ◽  
Alkylperoxy Radicals

Theoretical Investigation of Intramolecular Hydrogen Shift Reactions in 3-Methyltetrahydrofuran (3-MTHF) Oxidation

2015 ◽  
Vol 119 (44) ◽  
pp. 10917-10928 ◽  
Author(s):  
Prajakta R. Parab ◽  
Naoki Sakade ◽  
Yasuyuki Sakai ◽  
Ravi Fernandes ◽  
K. Alexander Heufer
Keyword(s):  
Theoretical Investigation ◽  
Hydrogen Shift ◽  
Intramolecular Hydrogen

Dissolution of Cellulose and Synthesis of Cellulose-Graft-Poly (L-Lactide) via Ring-Opening Polymerization in an Ionic Liquid

2012 ◽  
Vol 476-478 ◽  
pp. 1897-1900 ◽  
Author(s):  
Shu Xiao ◽  
Lin Dai ◽  
Jing He
Keyword(s):  
Ionic Liquid ◽  
Hydrogen Bonds ◽  
1H Nmr ◽  
Ring Opening ◽  
Graft Copolymerization ◽  
Ring Opening Polymerization ◽  
Intramolecular Hydrogen Bonds ◽  
Ft Ir ◽  
Intramolecular Hydrogen ◽  
Organic Catalyst

Dissolution and homogeneous graft copolymerization of cellulose were performed in an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) with L-lactide. The best synthetic condition of the cellulose-graft-poly (L-) (cellulose-g-PLLA) was that cellulose 0.6g, L-lactide 5.34g and 4-dimethylaminopyri lactide dine (DMAP) as an organic catalyst 0.69g reacted for 12 hours at 80°C. The synthesized AmimCl and cellulose graft copolymers were characterized by FT-IR, 1H-NMR, GPC, TG and WAXD. The results indicated that AmimCl dissolved cellulose directly by destroying intermolecular and intramolecular hydrogen bonds in cellulose and the grafting rate of the polymer reached 4.44, which was higher than that reported in AmimCl with Sn(oct)2 as a catalyst.

Sign in / Sign up

Export Citation Format

Share Document