Showing papers in "Journal of Organic Chemistry in 1985"

Proton-transfer steps in Steglich esterification: a very practical new method for macrolactonization

Abstract: ω-Hydroxysauren (I) lassen sich in verdunnter Losung in Gegenwart von DCC und von Dimethylaminopyridin (DMAP)-Hydrochlorid (II) in die Lactone (III) uberfuhren.

Ti(O-i-Pr)4-mediated nucleophilic openings of 2,3-epoxy alcohols. A mild procedure for regioselective ring-opening

Abstract: La presence de Ti(O-i-Pr) 4 au cours de l'ouverture d'epoxy-2,3 alcools avec une variete de nucleophiles augmente de facon importante la vitesse et la regioselectivite de ce processus

Allylzinc reagents additions in aqueous media

Abstract: Obtention d'alcools homoallyliques lorsque des halogenures d'allyle, zinc et aldehydes ou cetones sont soumis a une reaction sonochimique

Allylic carbonates. Efficient allylating agents of carbonucleophiles in palladium-catalyzed reactions under neutral conditions

Abstract: Allylation de β-cetoesters et du malonate de diethyle a l'aide des (alcene-1yl methyl) carbonates. Allylation par le diallylcarbonate de composes nitro, cyano, sulfonyles et carbonyles

A study on the photochemical dimerization of coumarins in the solid state

Abstract: Solid-state photochemical behavior of 28 substituted coumarins has been investigated. Of these twelve underwent photodimerization and this is remarkable in light of the inertness of coumarin itself in the solid state. X-ray crystallographic investigation of eight coumarins was undertaken with the view of understanding the role of packing in the crystal on their solid-state reactivity. Important findings include the identification of acetoxy and chloro substituents as useful “crystal engineering” groups and the results pertaining to subtler aspects of topochemical postulates. X-ray crystal structure analyses of 7-chlorocoumarin and 7-methoxycoumarin reveal packing modes which are not commonly met. The former is arranged in a \beta type packing, the center-center distance between the reactive double bonds being 4.454 \AA, which lies beyond the so far accepted limit of 3.5-4.2 \AA. The reactive double bonds of 7-methoxycoumarin, on the other hand, are rotated by $65^O$ with respect to each other with the center-center distance between the double bonds being 3.83 \AA. Inspite of these unfavorable arrangements photodimerization of the above two coumarins in the solid state occurs through a topochemical process with large dimer yields. A careful analysis of the X-ray crystallographic resulta obtained from our investigations reveals that the two double bonds in the reactive crystals may be displaced with respect to each other both along the molecular plane as well as along the double bond axis. Thus the normally accepted dictums that in the photoreactive crystals the doube bonds should be within a distance of 4.2 \AA, and that they be parallel are no longer operational.

Acetoacetylation with 2,2,6-trimethyl-4H-1,3-dioxin-4-one: a convenient alternative to diketene

Abstract: La pyrolyse de la trimethyl-2,2,6 4H-dioxinne-1,3one-4 en presence de nucleophiles constitue une bonne methode de preparation de derives acetylacetates

A convenient synthesis of 3-acylindoles via Friedel Crafts acylation of 1-(phenylsulfonyl) indole. A new route to pyridocarbazole-5, 11-quinones and ellipticine

Abstract: Application de la reaction de Friedel et Crafts d'acylation en 3 des benzenesulfonyl-1 indoles a la synthese de pyrido [3,4-b]- et -[4,3-b] carbazolequinones-5,11 (puis d'ellipticine) et de benzo [b] carbazolequinone-6,11 (acylation par l'anhydride ou le chlorure-3 et ester de methyle-4 de l'acide pyridinedicarboxylique-3,4 ou par l'anhydride phtalique)

The Horner-Wadsworth-Emmons modification of the Wittig reaction using triethylamine and lithium or magnesium salts

Abstract: Etude de la reaction du diethoxyphosphoryl acetate d'ethyle avec les benzaldehyde, heptanal, cinnamaldehyde, cyclohexanone et cyclopentanone

Zinc-Modified Cyanoborohydride as a Selective Reducing Agent

Abstract: Proprietes reductrices du cyanotrihydroborate modifie par le zinc, (genere a partir du cyanotrihydroborate de sodium et du chlorure de zinc dans un rapport molaire 2/1) dans la reduction de composes carbonyles selectionnes, la reduction d'enamines, l'amination reductrice d'aldehydes et cetones, la methylation reductrice d'amines et la desoxygenation d'aldehydes et cetones via l'intermediaire de tosylhydrazones

Selective oxidation of alcohols by oxoaminium salts (R2N:O+ X-)

Abstract: The selective oxidation of alcohols by use of an oxoaminium salt was investigated. The reaction proceeded clearly under mild condition with a satisfactory yield of carbonyl compounds uncomplicated by the presence of side products. The synthesis of oxoaminium salt IV was given. The oxidation of l-hexanol, 2-hexanol, and 3-hexanol by use of IVa (oxidant) in CH/sub 2/Cl/sub 2/ at room temperature was included. The oxidation rates of primary and secondary alcohols with IVa were studied. Primary alcohols were oxidized faster than secondary alcohols with IVa. 7 references, 2 figures, 2 tables.

Selective transformations of 2,3-epoxy alcohols and related derivatives. Strategies for nucleophilic attack at carbon-3 or carbon-2

Abstract: Etude des reactions d'epoxy-2,3 alcanols avec NaN 3 -NH 4 Cl dans le methoxy-2 ethanol, ou avec le benzenethiolate de sodium-benzenethiol dans le THF

The nature of the macromolecular network structure of bituminous coals

Abstract: The macromolecular network structure of bituminous coals has been studied by using the classical solvent-swelling techniques of polymer chemistry. Solutions of nonpolar solvents in coals follow regular solution theory. Solvents which are hydrogen bond acceptors show strongly enhanced solubility (coal swelling) which correlates with the strength of the hydrogen bond between the solvent and p-fluorophenol. A family of network active hydrogen bonds exists in bituminous coals. In native coals, their strength appears to range from 5 to 8 kcal/mol. The use of solvent-swelling data to calculate the number average molecular weight between cross-links (anti M/sub c/) has been explored. It is not yet possible to calculate correct absolute values for anti M/sub c/, but changes in anti M/sub c/ can be followed. The treatment of coals as macromolecular networks is possible and provides significant new insight into their structure. 39 references, 8 figures, 4 tables.

Selective transformation of 2,3-epoxy alcohols and related derivatives. Strategies for nucleophilic attack at carbon-1

Abstract: Obtention dans les conditions de la transposition de Paynes de t-butylthio-1 alcanediols-2,3

The design of resolving agents - chiral cyclic phosphoric-acids

Abstract: Synthese et structure cristalline du chloro-2' phenyl-4 dimethyl-5,5 dioxaphosphorinanne-1,3,2ol-2 oxyde-2