Philip M. Keehn

The oxidation of alcohols and ethers using calcium hypochlorite [Ca(OCl)2]

Abstract Calcium hypochlorite, a relatively stable, and easily stored and used solid hypochlorite oxidant, was found to oxidize secondary alcohols to ketones in excellent yields. Primary alcohols gave esters where both the acid and the alcohol portions of the esters were derived from the alcohol. Ethers were oxidized to esters though only in moderate yield.

The oxidation of aldehydes to acids with calcium hypochlorite [Ca(OCl)2]

Abstract Calcium hypochlorite is an efficient reagent for the oxidation of aldehydes to the corresponding acids. Reactions are carried out at ambient temperature in aqueous acetonitrile-acetic acid solution. Aliphatic aldehydes and aromatic aldehydes with electron withdrawing groups afford good to excellent yields. Nuclear chlorination is the preferred reaction in aromatic aldehydes with electron donating groups.

Oxidative cleavage of α-diols, α-diones, α-hydroxy-ketones and α-hydroxy- and α-keto acids with calcium hypochlorite [Ca(OCl)2].

Abstract α-Diols, α-diones, α-hydroxy ketones, and α-hydroxy- and α-keto acids are easily cleaved oxidatively with calcium hypochlorite. The reaction is carried out at ambient temperature in aqueous acetonitrile/acetic acid solution. The yields are good to excellent and the products, depending on the starting material, are aldehydes, ketones or acids.

High yield synthesis of the parent C-unsubstituted calix[4]resorcinarene octamethyl ether

Treatment of 2,4-dimethoxybenzyl alcohol with trifluoroacetic acid (TFA, 5% in CHCl3) affords, in almost quantitative yield calix[4]resorcinarene octamethyl ether, which on demethylation and acetylation yields the derived octa-acetate.

Active MnO2. Oxidative Dehydrogenations

Abstract We recently required substantial quantities of 5,8-disubstituted naphthoquinone IV as a precursor for the synthesis of a cyclophane. The sequence chosen to provide the necessary intermediate (IV) utilized a Diels-Alder reaction, between I and p-benzo-quinone, followed by aromatization. Several attempts however at dehydrogenating adduct II (Br2;2 air;3 DDQ or chloranil4) failed, or afforded poor conversions (10–25%). During our research, a report appeared describing the use of commercial grade MnO2in the oxidation of hydroquinones to quinones. 5 Encouraged by the results described in the publication we attempted the oxidation of II with MnO2. When adduct II was stirred in benzene with ordinary MRO2

Ring Chlorination of Benzenoid Compounds Using Calcium Hypochlorite [Ca(OCl)2]

Abstract Chlorination of activated benzenoid rings is efficiently effected at 0 °C in aqueous acetone/HOAc using calcium hypochlorite as the chlorinating agent. Good to excellent yields of the chlorinated products are obtained.

Cyclophanes—13: Crystal and molecular structure of [2.2][2,5]furano(1,4)naphthalenophane

Abstract The crystal and molecular structure of [2.2](2,5)furano(1,4)naphthalenophane (1) was determined by X-ray crystallography. The molecule exists in the anti-conformation and the study represents the first instance in which the structural features of a naphthalenoid ring within a cyclophane were determined. Crystals of cyclophane 1 are orthorhombic, space group Pbca, with a = 7.859(2). b = 11.482(3) and c = 28.818(8) A. While the nonbridged portion of the naphthalenoid ring is planar, the portion which is bridged to the furanoid ring through its 1 and 4 C atoms is puckered and boat-shaped. These C atoms are positioned 14° out of the plane of the other four C atoms of this ring. The furanoid ring is essentially planar but is not parallel to the naphthalenoid ring. It is inclined 22° to the least squares plane of the bridged portion of the naphthalenoid ring. This angle of inclination staggers the atoms of the furanoid and bridged naphthalenoid ring and positions the 3 and 4 C atoms, the 2 and 5 C atoms and the 0 atom of the furanoid ring 3.4. 2.9 and 2.6 A. respectively, from the least squares plane of the bridged portion of the naphthalenoid ring. While the internal angles around the bridging C atoms α- to the naphthalenoid ring are 109°, those α- to the furanoid ring are 113°. In addition unusually large bond angles (

Cyclophanes—VII : Conformations of [2.2](2,5)furanoparacyclophane,[2.2](2,5)furano(1,4)naphthalenophane and [2.2](2,5)furano(9,10)anthracenophane. perpendicularity of aromatic moieties

137°) at the 2 and 5 C atoms of the furanoid ring, external to the ring, are also observed. The distortions are considered with respect to the strain within the cyclophane macrocycle and are compared with other similar systems.

Epoxide Ring Opening by α-Sulfonyl Carbanions. Synthesis of γ-Hydroxy Sulfones and Triflones

Abstract Variable temperature NMR spectroscopy was used to study the conformational behavior of [2.2](2,5)furanoparacyclophane ( 1 ), [2.2](2,5)furano(1,4)naphthalenophane ( 2 ) and [2.2](2,5)furano(9,10)anthracenophane ( 3 ). While the method was useful in studying 1 , it was not adequate for 2 and 3 . Variable temperature UV absorption and fluorescence emission studies provided information on the conformations of 2 and 3 . The UV absorption and emission spectra of 1 were blue-shifted relative to their ambient temperature spectra. Those of 2 were not shifted at all and those for 3 were red-shifted. The data is consistent with an anti -orientation of the aromatic rings in 2 both at ambient and low temperture. The aromatic rings in 3 are perpendicular to one another at low temperature and probably at room temperature as well. Exiplex bands were absent in the room temperature emission spectra of 1 , 2 and 3 as well as the low temperature spectra of 2 and 3 . An exciplex band was observed in the low temperature emission spectrum of 1 .

Halogenated analogs of tri-O-thymotide (TOT) and tri-3-(2-butyl)-6-methylsalicylide (TSBS): synthesis and clathration studies.

Abstract γ-Hydroxy sulfones and triflones are obtained in moderate to excellent yields when n-butyl lithium is added to a mixture of sulfone and epoxide in toluene at 65[ddot] C followed by heating from four to twenty hours at 110[ddot] C.