Lithium Perchlorate In Diethyl Ether Research Articles

LPDE-Catalyzed Intramolecular Cyclization of Arylimines: A Facile Synthesis of Tetrahydrochromanoquinolines

Lithium perchlorate in diethyl ether (LPDE) is found to catalyze an intrarmolecular cyclization of aldimines derived from aromatic amines and O-prenyl derivatives of salicylaldehydes to afford the corresponding tetrahydrochromano[4,3-b]quinoline derivatives in excellent yields with moderate diastereoselectivity.

Studies of the Catalysis of Ene Reactions of 4-Phenyl-1,2,4-triazoline-3,5-dione and Diethyl Azodicarboxylate with Different Olefins by Lithium Perchlorate

The catalytic effect of lithium perchlorate in diethyl ether on ene reaction of 2-hexene, cyclohexene, 1-methylcyclohexene, oleic acid and methyl oleate with 4-phenyl-1,2,4-triazoline-3,5-dione has been studied, as well as on the reaction of diethyl azodicarboxylate with methyl oleate.

Oxabicyclo[3.2.1]octenes in organic synthesis: direct ring opening of oxabicyclo[3.2.1] ring systems with diisobutylaluminum hydride and a silyl ketene acetal--synthesis of the chiral C(19)-C(26) and C(27)-C(32) fragments of Scytophycin C.

[reaction: see text] An efficient strategy for transforming meso-oxabicyclo[3.2.1]octenone 1 into optically active intermediates for macrolide synthesis has been developed. The direct bridgehead opening of optically active oxabicyclo[3.2.1]octene derivative 2 with hydride or a silyl ketene acetal utilizing the highly polar medium lithium perchlorate in diethyl ether resulted in highly functionalized cycloheptenones, which were transformed into the C(19)-C(26) and C(27)-C(32) fragments of Scytophycin C.

Lithium Perchlorate/Diethylether Catalyzed Aza-Diels-Alder Reaction: An Expeditious Synthesis of Pyrano, Indeno Quinolines and Phenanthridines

Lithium perchlorate in diethylether (LPDE) is found to catalyze imino-Diels-Alder reactions of N-aryl aldimines with 3,4-dihydro-2H-pyran (DHP), indene, and cyclohexenone to afford the corresponding pyrano, indeno quinolines and phenanthridinone derivatives in high yields.

A simple one-pot three-component reaction for preparation of secondary amines and amino esters mediated by lithium perchlorate

The one-pot synthesis of several secondary amines and secondary amino esters are reported. Treatment of aldehydes (aliphatic or aromatic) with (trimethylsilyl)alkylamines, in the presence of 5 M lithium perchlorate in diethyl ether gives intermediate imines. Reaction of these intermediate imines with different nucleophiles and functionalized organozinc reagents, BrZnCH 2COOR, produce a variety of secondary amines and N-alkyl- or N-arylamino esters in good yields.

ChemInform Abstract: Oxabicyclo[3.2.1]octenes in Organic Synthesis—Direct Ring Opening of Oxabicyclo[3.2.1] Systems Employing Silyl Ketene Acetals in Concentrated Solution of Lithium Perchlorate—Diethyl Ether: Application to the Synthesis of the C(19)—C(27) Fragment of Rifamycin S.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Oxabicyclo[3.2.1]octenes in organic synthesis--direct ring opening of oxabicyclo[3.2.1] systems employing silyl ketene acetals in concentrated solutions of lithium perchlorate-diethyl ether: application to the synthesis of the C(19)-C(27) fragment of rifamycin S.

[figure: see text] The direct opening at the bridgehead of oxabicyclo[3.2.1]octenes employing silyl ketene acetals in 4.0-5.0 M lithium perchlorate in diethyl ether has been realized, which gives rise to highly functionalized cycloheptadienes that can be further manipulated for use in natural product synthesis. The bridgehead opening reaction has been employed in the construction of the C(19)-C(27) fragment of Rifamycin S.

Preparation of Aminovinyl Phosphonates by Four-Component Aminoalkylation of Aldehydes Mediated by Lithium Perchlorate

Several aminovinyl phosphonates were prepared in good yield by four-component aminoalkylation of aldehydes with diethyl(trimethylsilyl)amine, triethylphosphite and dimethyl acetylenedicarboxylate mediated by a 5 molar solution of lithium perchlorate in diethyl ether.

Highly Selective Synthetic Transformations Catalyzed by Lithium Perchlorate in Organic Media

Highly concentrated solutions of lithium perchlorate in various organic solvents have been used as media for many synthetic transformations at room temperature which are otherwise difficult to carry out under ordinary conditions. The rates of several organic reactions are faster in these media compared than in pure solvents. More importantly high chemo-, regio- and stereoselectivities have been observed. The mild Lewis acidity of the lithium ion in donor solvents such as diethyl ether is responsible for these selectivities. Fine tuning of the Lewis acidity of the lithium ion, depending upon the solvent basicity and polarity, has been possible for selective activation of organic substrates in these media. The activation of carbonyl- and other oxygen-containing organic compounds in 5 M lithium perchlorate in diethyl ether (LPDE) and in nitromethane (LPNM) is presented.

高極性反応場を用いるカチオンディールス・アルダー反応の開発と天然物合成への応用

Our longstanding interest in the Diels-Alder reactions led us to examine lithium perchlorate in diethyl ether (LPDE) as a medium for effecting [4 + 2] cycloadditions, despite the general view that the rate of the Diels-Alder reaction is essentially independent of solvent polarity. This article describes an effecient, synthetically useful protocol for the construction carbocyclic systems via intramolecular cationic Diels-Alder reactions of in situ-generated heteroatom-stabilized allyl cations in highly polar media. We also present that use of catalytic acid in LPDE to promote intramolecular Diels-Alder reactions of conformationally restricted substrates possessing terminal dienes results in acid catalyzed migration of the diene prior to [4 + 2] cycloaddition.

Lithium Perchlorate Mediated Three Component Reaction for the Preparation of Primary Amines

In the presence of lithium perchlorate in diethyl ether, LPDE, a three-component reaction between aldehydes, sodium hexamethyldisilazane or lithium hexamethyldisilazane, LHMDS, and different nucleophiles proceeds smoothly to afford primary amines in good yields.

Chemical and Spectroscopic Studies Related to the Lewis Acidity of Lithium Perchlorate in Diethyl Ether

Polarimetric studies on camphor (2) as well as IR studies on crotonaldehyde (CA; 1) and benzonitrile (BN; 3) confirm the conclusion of a previously published NMR study on crotonaldehyde that lithium perchlorate (LP) weakly binds to probe bases in diethyl ether (DE). The weak binding is a consequence of the fact that the lithium ion (actually the LP ion pair and higher aggregates), a powerful Lewis acid in the gas phase, competitively binds to ether and the added base. Methylene camphor (5), (E)-1,3-pentadiene (4), camphene, and phenylacetylene (6) do not bind to LP in DE. Shifts to lower energy of the CO modes of CA in ether solutions containing increasing amounts of LP are consistent with moderate increases in solvent polarity. Only small or no shifts are seen in the C⋮N modes of BN and its 1:1 complex with added LP. Because the C⋮N and especially CO modes are blue shifted under external applied pressure, the large internal pressures of LP/DE do not mimic external applied pressure. Likewise, the small or...

ChemInform Abstract: Mild and Efficient Tetrahydropyranylation of Alcohols — Catalysis by Lithium Perchlorate in Diethyl Ether.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Lithium Perchlorate Mediated Three Component Reaction for the Preparation of Primary Amines

In the presence of lithium perchlorate in diethyl ether, LPDE, a three-component reaction between aldehydes, sodium hexamethyldisilazane or lithium hexamethyldisilazane, LHMDS, and different nucleophiles proceeds smoothly to afford primary amines in good yields.

Highly chemo- and regioselective rearrangement of α,β-epoxy ketones to 1,3-dicarbonyl compounds in 5 mol dm−3 lithium perchlorate–diethyl ether medium

Epoxides from α,β-unsaturated ketones undergo highly chemo- and regioselective rearrangement to 1,3-dicarbonyl compounds in 5 mol dm–3 lithium perchlorate–diethyl ether medium by a 1,2-migration of the carbonyl group at ambient conditions.

Chemoselective aldol condensation in 5 mol dm−3 lithium perchlorate–nitromethane. A comparison with lithium perchlorate–diethyl ether medium

Aldol reactions of silyl enol ethers with aldehydes proceed in 5 mol dm–3 lithium perchlorate–nitromethane medium at ambient temperature. The reaction is highly chemoselective such that only aldehydes and cyclic ketones reacted while acyclic and aromatic ketones failed to react. The same reaction is not promoted in 5 mol dm–3 lithium perchlorate–diethyl ether medium. The difference between these two media is explained by the increased Lewis acidity of the lithium ion in nitromethane compared to that in ether.

Diels–Alder reactions in ionic liquids

Diels–Alder reactions in neutral ionic liquids (such as 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium tetrafluoroborate, and 1-butyl-3-methyl-imidazolium lactate) are reported. Rate enhancements and selectivities similar to those of reactions performed in lithium perchlorate–diethyl ether mixtures have been observed. As the ionic liquids used have no measurable vapour pressure, are thermally robust, will tolerate impurities such as water, and are recyclable, it is envisaged that these systems could be used on an industrial scale.

Mild and efficient tetrahydropyranylation of alcohols-catalysis by lithium perchlorate in diethyl ether

Treatment of 3,4-dihydro-2 H-pyran 1 with various alcohols 2 – 10 furnished the tetrahydropyranyl ethers 11 – 19 in the presence of 5 M lithium perchlorate in diethyl ether (5 M LPDE), which is essentially a neutral medium.

Mechanism of Lithium Perchlorate/Diethyl Ether-Catalyzed Rearrangement of α- and β-endo- and -exo-Dicyclopentadienyl Vinyl Ethers: Use of Deuterium Labeling and a Chiral Probe

Lithium perchlorate/diethyl ether (LPDE) mediated rearrangement of α- and β-endo-dicyclopentadienyl vinyl ethers 5 and 6 resulted in the formation of the aldehyde 8, indicating that the mechanism is nonconcerted and the recombination of the ion pair occurs at the dissociated stage and not the intimate ion-pair stage. Proof of this came from deuterium-labeling studies and the use of an optically pure starting material. Furthermore, that the ionic intermediate formed must be symmetrical resulting in enantiomeric aldehydes from both normal and allylic attack corresponding to products of formal 1,3 and 3,3 shifts was seen in the chiral analysis of the benzoate derivative of the aldehydes formed from the optically pure vinyl ether.

Origins of Stereocontrol in the [2 + 2] Cycloaddition between Achiral Ketenes and Chiral α-Alkoxy Aldehydes. A Pericyclic Alternative to the Aldol Reaction

Ab Initio calculations predict that the thermal [2 + 2] cycloaddition reaction between C2v-symmetric ketenes and enantiopure aldehydes takes place with high enough stereocontrol for preparative purposes. The sense of induction is predicted to be non-Felkin. It is also found that the [2 + 2] cycloaddition involving nonactivated ketenes is facilitated by using 5 M solutions of lithium perchlorate in diethyl ether. It is found that both the purely thermal and lithium-assisted [2 + 2] cycloadditions result in the same type of stereocontrol. This method constitutes a general route for the synthesis of homochiral 2-oxetanones and related compounds, thus providing a pericyclic alternative to the aldol reaction.