Lithium Perchlorate In Diethyl Ether Research Articles

Solvate Ionic Liquids as Reaction Media for Electrocyclic Transformations

AbstractSolvate ionic liquids (SILs) consisting of lithium bis(trifluoromethylsulfonyl)imide dissolved in tri‐ or tetraglyme have recently emerged as a novel class of ionic liquids. Herein, the first use of solvate ionic liquids as a replacement for molecular solvents in electrocyclization reactions is reported. The SILs promoted both Diels–Alder and [2+2] cycloaddition reactions, compared to an appropriate molecular solvent, and 5 M lithium perchlorate in diethyl ether. The Gutmann acceptor number (AN) of these solvate ionic liquids has also been determined by 31P NMR spectroscopy to be 26.5, thus being modest Lewis acids.

ChemInform Abstract: Lithium Perchlorate Accelerated Friedel—Crafts Addition of Furans to β‐Nitrostyrenes.

The Friedel-Crafts alkylation of furans by the Michael acceptor, β-nitrostyrene, is greatly accelerated by the use of the Lewis acid catalyst and solvent, 5 M lithium perchlorate in diethyl ether (LDPE).

Lithium perchlorate accelerated Friedel–Crafts addition of furans to β-nitrostyrenes

The Friedel–Crafts alkylation of furans by the Michael acceptor, β-nitrostyrene, is greatly accelerated by the use of the Lewis acid catalyst and solvent, 5M lithium perchlorate in diethyl ether (LDPE).

ChemInform Abstract: (1,3) Sigmatropic Rearrangement of Allyl Vinyl Ethers at Ambient Temperature in 3.0 M Lithium Perchlorate-Diethyl Ether.

ChemInform 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.

ChemInform Abstract: Chelation Controlled Addition of Allylstannanes to Aldehydes in Lithium Perchlorate-Diethyl Ether.

ChemInform 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.

ChemInform Abstract: 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 addition of organometallics to oxime ethers

In this paper, an efficient method for preparation of various substituted hydroxylamines from aldehydes is reported. We first prepare O-trimethylsilyl oxime ether in 5 M solution of lithiumperchlorate in diethyl ether (LPDE 5M) from condensation reaction between aldehyde and O-trimethylsilyl hydroxylamine, then add organosilane or organotin nucleophile in the same vessel to preparing the corresponding α-substituted hydroxylamines in one-pot synthesis.

One-pot, three-component synthesis of secondary amines and trisubstituted hydrazines from ketones

AbstractVarious imines and hydrazones were reduced to the corresponding amines and hydrazines using borane-tetrahydrofuran complex as a reducing agent in the solution of lithium perchlorate in diethyl ether. The initial imines or hydrazones have been prepared at the same conditions just before the reduction step. Both steps were carried out in one vessel with a good yield and insignificant formation of by-products.

An Efficient and Improved Method for the Synthesis of Bis(arylmethylidene)thiopyranones.

Double crossed aldol condensation of a variety of aromatic aldehydes with tetrahydrothiopyran-4-one in the presence of N-(trimethylsilyl)diethylamine and 5 M lithium perchlorate in diethyl ether at room temperature is described. Excellent yields of 3,5-bis(arylmethylidene)thiopyranones are achieved in a facile one-pot general procedure.

An Efficient Route to 4/5/6 Polycyclic β‐Lactams.

AbstractFor Abstract see ChemInform Abstract in Full Text.

An Efficient and Improved Method for the Synthesis of Bis(arylmethylidene)thiopyranones

Double crossed aldol condensation of a variety of aromatic aldehydes with tetrahydrothiopyran-4-one in the presence of N-(trimethylsilyl)diethylamine and 5 M lithium perchlorate in diethyl ether at room temperature is described. Excellent yields of 3,5-bis(arylmethylidene)thiopyranones are achieved in a facile one-pot general procedure.

An Efficient Route to 4/5/6 Polycyclic β‐Lactams

AbstractThe synthesis of 4/5/6 polycyclic β‐lactams by enyne metathesis and Diels−Alder reactions is described. Compared to the synthesis of 4/6/6 and 4/7/6 polycyclic β‐lactams previously reported by our laboratory, formation of the strained 4/5/6 compounds requires alternative reaction conditions. Indeed, the synthesis of the 4/5 bicyclic diene 12 was more difficult than those of the 4/6 (13) and 4/7 (14) dienes. The strain of the 4/5 system could be observed by NMR spectroscopy and molecular modelling. Moreover, the reactivity of 4/5 diene 12 towards Diels−Alder cycloaddition was also different from that of the 4/6 (13) and 4/7 (14) dienes. Cycloadditions with 4/5 diene 12 therefore had to be performed in lithium perchlorate/diethyl ether (LPDE) or in an ionic liquid in order to proceed in good yields with various dienophiles. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

A Novel Procedure for Conversion of Epoxides to α‐Hydroxyphosphonates with a Trialkylphosphite‐Mediated by LiClO4.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A novel procedure for conversion of epoxides to α-hydroxyphosphonates with a trialkylphosphite mediated by LiClO4

A new method has been developed for the direct conversion of epoxides to α-hydroxyphosphonates by the reaction of a trialkylphosphite with the epoxide in 5 M lithium perchlorate in diethyl ether (LPDE). The reaction is highly regioselective and efficient with excellent yields under mild and neutral conditions.

Lithium Perchlorate Diethyl Ether Solution: A Highly Efficient Media for the Abramov Reaction

The f -hydroxy phosphonates are readily prepared by treating aromatic or aliphatic aldehydes and ketones with trialkylphosphite in the presence of trimethylsilylchloride in a very short time and in almost quantitative yields.

LiClO4-Catalysed C-Alkylation of Pyrrole and Indoles with Aziridines and Epoxides

Aryl- N-tosylaziridines and epoxides smoothly undergo ring-opening with pyrrole and indoles in the presence of 5M lithium perchlorate in diethyl ether (LPDE) at ambient temperature to afford the corresponding 2- and 3-alkylated pyrroles and 3-alkylated indoles in high yields with high selectivity. LiOTf is also found to be an effective catalyst for this transformation.

A new protocol for the one-pot preparation of highly diastereomerically enriched secondary amines and β-amino esters mediated by lithium perchlorate solution in diethyl ether

A highly diastereoselective one-pot, three-component method for the preparation of several secondary amines and amino esters is reported. Treatment of aldehydes (aliphatic or aromatic) with chiral amines and functionalized organozinc reagents (e.g. BrZnCH 2COOR, allylzinc bromide) in the presence of trimethylsilylchloride with 5 M lithium perchlorate in diethyl ether produces N-alkylamino esters or N, N-dialkylamines in good yields and high diastereoselectivities. The diastereomeric ratios of the secondary amines prepared by this method were lower in comparison to those of the N-alkylamino esters formed in the same way.

LPDE‐Catalyzed Intramolecular Cyclization of Arylimines: A Facile Synthesis of Tetrahydrochromanoquinolines.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Modulation of tautomeric equilibria by ionic clusters. Acetylacetone in solutions of lithium perchlorate-diethyl ether.

Acetylacetone (2,4-pentanedione, 1) is a molecule whose tautomeric forms are in dynamic equilibrium. Concentrated salt solutions in nonaqueous solvents exert a remarkable influence on the keto-enol ratio of this beta-diketone. The keto content of 1 increases from 5% in pure diethyl ether to 84.5% in a 4.14 M lithium perchlorate-diethyl ether (LPDE) solution, a nearly 17-fold increase. The equilibrium expression, K = [keto]/[enol] = k(f)/k(r), exhibits a linear dependence on [LiClO(4)], with the formal order of participation of lithium ion in the equilibrium being 1.0. A kinetic analysis reveals that k(f) is independent of LPDE concentration, whereas k(r) displays an inverse dependence on salt concentration, indicating preferential coordination of the keto tautomer with Li(+). Although 1 exits as the enol in water only to the extent of 16%, the addition of lithium perchlorate further reduces this figure. In an aqueous 4.02 M LiClO(4) solution, acetylacetone enol accounts for only 4.6% of the total amount of 2,4-pentanedione present. It has also been found that acetylacetone itself is an excellent solvent for LiClO(4) as well as for NaClO(4) with solutions containing up to 7.5 M LiClO(4) attainable. The enol content of 1 decreases dramatically from 81% to 7.4% on going from the neat liquid to a solution of 6.39 M LiClO(4) in acetylacetone.

Electrostatic modulation by ionic aggregates: charge transfer transitions in solutions of lithium perchlorate-diethyl ether.

The ionic environment within solutions of lithium perchlorate-diethyl ether (LPDE) was probed by utilizing the extraordinary spectral shifts these media impart on various nitroanilines at 25 degrees C. These compounds all have UV-visible spectra that are sensitive to the polarity of the medium and the nitroanilines investigated all exhibited varying degrees of solvatochromatic behavior in LPDE solutions. In all cases, the low-energy absorbance band exhibited a dependence upon LiClO(4) concentration throughout the entire solubility range investigated. For 4-nitroaniline and N,N-dimethyl-4-nitroaniline bathochromic shifts of 51.3 and 62.0 nm, respectively, were observed on going from pure ether to a 5.7 M LPDE solution, corresponding to a stabilization of 10.55 and 11.13 kcal mol(-1), respectively, for this transition. Thus, as the medium changes from diethyl ether to one containing ionic clusters of lithium perchlorate-diethyl ether, less energy is required to transfer the molecules from their ground states to their first excited states. For 2,6-dibromo- and 2,6-diiodo-4-nitroaniline smaller red shifts of 19.0 and 9.0 nm, respectively, were noted over the same concentration range of LPDE, resulting in stabilizations of 4.45 and 2.11 kcal mol(-1), respectively. Analysis of the observed molar transition energies indicates that for 4-nitroaniline and N,N-dimethyl-4-nitroaniline the stabilization of the zwitterionic excited states of such push-pull molecules is on the order of 2.0 kcal mol(-1) per mol of added salt. Furthermore, such stabilization is independent of the composition of the media. Thus these compounds can act as solvent polarity indicators for LPDE solutions throughout the entire solubility range of LiClO(4) in diethyl ether. As such, linear relationships are seen between the E(T) values of 4-nitroaniline and N,N-dimethyl-4-nitroaniline and the log of the second-order rate constants for the [4+2] cycloaddition reaction of 9,10-dimethylanthracene and acrylonitrile in LPDE. We also observe linear relationships between the E(T) values of 4-nitroaniline and N,N-dimethyl-4-nitroaniline and the keto-enol ratio of acetylacetone in LPDE.