Insight into the unusual reactions of stabilized phosphorus ylides with lactols. A specific intramolecular hydroxyl group effect leads to high z-selectivity.

In reactions with stabilized ylides, γ-lactols of ribo configuration afford 90% Z-olefins whereas γ-lactols of allo configuration afford predominantly E-olefins. Lactols of arabino configuration give intermediate results. The unusual results in the ribo series completely disappear on protection of the γ-hydroxyl group.     

Nitrone cycloadditions. regiochemistry.

The regiochemistry of nitrone cycloadditions has been reexamined. Certain nitrones afford regioisomeric mixtures of isoxazolidines, with a tendency toward increasing amounts of the 4-substituted regioisomer as the ionization potential of the dipolarophile is increased.     

Palladium-Catalyzed Reaction of 1,3-diene monoepoxides with sodium azide. 1,4-Azidohydroxylation of conjugated dienes.

Palladium-catalyzed regioselective 1,4-addition of sodium azide to vinylepoxides afford 4-azido-2-alkenols in good yields.     

Solute-Solvent Interactions : Vol 2, J.F. Coetzee and C.D. Ritchie (Editors), M. Dekker Inc., New York and Basel, 1976, ix + 459, Swiss Fr. 125.

In the presence of catalytic amounts of chlorotris(triphenylphosphine)-rhodium(I), the reaction of acyl chlorides with allyltri-n-butyltin proceeded smoothly under mild conditions to afford the corresponding allyl ketones.     

Hypervalent Iodine in Synthesis. VI. The Electrophilic Arylation of Diaryliodonium Salts to Sodium Telluride

Diaryliodonium salts readily take place electrophilic arylation at Te to afford symmetrical diaryl tellurides in good yields.     

Dilithium tetrachlorocuprate. A reagent for regioselective cleavage of epoxides to chlorohydrins.

The title compound reacts with epoxides to selectively afford the vicinal chlorohydrin resulting from attack by chloride at the less substituted carbon atom.     

The reaction of isothiocyanates with 2-cyanoethanoic acid hydrazide. A novel synthesis of 1,3,4-thiadiazoles

Benzoyl and ethoxycarbonyl isothiocyanates reacted with 2-cyanoethanoic acid hydrazide 2 to afford 1-cyanoacetyl-4-substituted thiosemicarbazide ( 5a,b ). Compound 5a afforded the pyrazolo[1,5-a]-s-triazine derivative 6 on treatment with 5% potassium hydroxide, and cyclised to 2-benzoylamino-5-cyanomethyl-1,3,4-thiadiazole ( 8 ) when boiled under reflux in glacial acetic acid. Compound 8 condensed with aromatic aldehydes to yield the corresponding arylidene derivatives 9a-c . It undergoes coupling with aromatic diazonium salts to afford the hydrazones 11a-c . Similarly, it coupled with diazotised aminopyrazole to afford the cyclic product 12 .     

S-silyketene s,n-acetals. cross-aldol type condensation reaction with schiff bases.

S-silylketene S,N-acetals react with Schiff bases to afford β-aminothioamide in good yields. The reactivity of the title acetals is compared to that of corresponding lithium-enethiolates.     

Copper(I) acetylide induced substitution in allylic ethers of benzothiazole. Regio- and stereoselective synthesis of 1,4-enynes.

Allylic ethers of benzothiazole react with copper(I) acetylides to afford 1,4-enynes under complete regio- and stereoselective control.     

Avermectin-milbemycin studies. 4. An expedient two-step preparation of p-hydroxybenzoates

Dianions derived from a variety of 1,3-diketones react with $\text{Z}$-ethyl-3-bromopropenoate to afford unsaturated diketoesters which upon treatment with base undergo facile cyclization-dehydration to p-hydroxybenzoates.     

Reactions of isocyanides. II- addition to acetals

In the presence of TiCl₄, tert-butyl isocyanide reacts with aldehyde acetals to afford β-alkoxycyanoenamines.     

1,2,4-Triazines. XII. Syntheses of 5-carboxarnido-1,2,4-triazines via an addition-oxidation reaction

5-Unsubstituted 1,2,4-triazines, when treated with potassium cyanide suspended in moist dioxane afford 5-carhoxamido as well as 5,5′ -bi-1,2,4-triazinyl derivatives. A probable reaction sequence is described.     

Copper complex protection in the regioselective alkylation of methyl 3,5-dioxohexanoate. Preparation of 3-alkyl derivatives of 4-hydroxy-6-methyl-2-pyrone

Protection of the diketone moiety of the polyketide model methyl 3,5-dioxohexanoate by copper(II) complex formation followed by alkylation of the free C-2 position results in overall regioselective alkylation of the diketoester to afford methyl 2-alkyl-3,5-dioxohexanoates, which under cyclization afford 3-alkyl derivatives of triacetic acid lactone.     

Condensed heterocycles. 48. Benzo[b]furan mercapto- and selenolaldehydes in the synthesis of bifunctional and complex-forming compounds

2-Bromo-3-benzo[b]furaldehyde and 3-chloro-2-benzo[b]furaldehyde react with sodium hydrosulfide or hydroselenide to give isomeric mercapto- and selenolbenzo furaldehydes, which afford the S (or Se) alkyl derivatives on reaction with ethyl chloroacetate, and Schiff bases on reaction with ethylenediamine hydrochloride. In the presence of sodium ethoxide, the S- and Sealkylated mercapto- and selenolaldehydes cyclize to thieno- and selenobenzofurans, while the Schiff bases afford chelate complexes with nickel and copper acetates.For previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 422–427, February, 1990.     

Synthesis of heterocycles. Part V. The synthesis of substituted indenopyridines

2-Arylmethylene-l-indanones (I) and 2-arylmethylene-1,3-indanediones (VII) react with active methylene compounds in the presence of ammonium acetate as a basic catalyst to afford substituted pyridines. The postulated routes to the formation of the reported compounds are given.     

Acetonitrile derivatives as carbonyl synthons. One-pot preparation of diheteroaryl ketones via a strategy of sequential SNAr substitution and oxidation

The anion of 2-aryl acetonitrile derivatives reacted with a variety of heteroaryl chlorides or bromides in an S(N)Ar manifold to afford intermediate anions which were susceptible to oxidation. The addition of sodium peroxide and aqueous NH(4)OAc solution effected oxidation to afford aryl heteroaryl ketones in good yields. Aryl acetonitrile derivatives are thus umpolung-type synthons of the corresponding aryl carbonyl functionality.     

Synthesis of a teichoic acid fragment of bacillus var.niger w.m. by a phosphotriester approach

Three properly-protected derivatives, one non-terminal and two terminal units, of 3-0-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl)-sn-glycerol have been joined together by two interglyceridic (2→1) phosphotriester linkages to afford, after removal of all protective groups, a teichoic acid fragment.     

Reaction of schiff bases with acrylamides. Synthesis of 2-oxotetrahydropyridines

Ketimines react with acrylamide and methacrylamide in the presence of aluminium chloride to afford 2-oxotetrahydropyridines by a C-alkylation pathway.     

Organocerium reagents. Nucleophilic addition to easily enolizable ketones

Organocerium reagents, prepared from organolithiums and anhydrous cerium (III) chloride, react cleanly with easily enolizable ketones to afford the addition products in good to excellent yields.     

Nitrogen bridgehead compounds. Part 60. Unusual amination with sodium azide.

9-Bromo-6,7,8,9-tetrahydro-4$\text{H}$-pyrido [1,2-$\text{a}$]pyrimidin-4-ones react with sodium azide to afford 9-amino-6,7-dihydroanalogues. A mechanism involving a tricyclic tetrazine intermediate formed by neighbouring-group participation is suggested.