Synthesis and some transformations of bicyclic γ-lactones with a fused cyclopropane ring

Reductive cyclization of 4-hydroxymethyl-5,5-dimethyl(or pentamethylene)-2,5-dihydrofuran-2-ones by the action of sodium tetrahydridoborate gave bicyclic compounds in which the lactone ring is fused to a cyclopropane ring. Hydrolysis of the products with aqueous sodium hydroxide resulted in the formation of the corresponding disodium cyclopropane-1,1-dicarboxylates, which reacted with alkyl halides to produce the diesters. Acid hydrolysis of the fused systems was accompanied by opening of the cyclopropane ring with formation of 4-chloromethyl-5,5-dimethyl-2-oxotetrahydrofuran-3-carboxylic acid.     

Stereoselective synthesis of γ-lactone fused cyclopentanoids

The stereoselective synthesis of γ-lactone fused cyclopentanoids applying chemoenzymatic methods is described. rac-2-Hydroxymethyl-1,4,5,6-tetrachloro-7,7-dimethoxybicyclo[2.2.1]hept-5-ene and rac-2-hydroxymethyl-1,4,5,6,7,7-hexachlorobicyclo[2.2.1]hept-5-ene were successfully resolved by Candida rugosa lipase (CRL), to afford enantiomerically enriched products with an ee of 94 and 97%, respectively. The enantiomerically enriched acetates were then subjected to ruthenium and/or cerium catalyzed oxidation to afford α-diketones and subsequent alkaline H₂O₂ mediated oxidative cleavage reaction of α-diketones, followed by CH₂N₂ esterification, gave enantiomerically enriched γ-lactone fused cyclopentanoids with known absolute configurations.     

Palladium-catalyzed epimerization of γ-alkenyl-γ-butyrolactone derivatives

γ-Alkenyl-α,β,γ-trisubstituted-γ-butyrolactones (12-16) and γ-alkenyl-furofurandione derivatives (21-Z-24-Z; 21-E-24-E; 25-Z-28-Z; and 25-E-28-E) were successfully epimerized in high yield by a palladium catalyst.     

Synthesis of γ-mercuridinitrohydrocarbons

Summary The denitration of -mercurinitro compounds has been studied and the corresponding organomercury dinitro derivatives have been obtained.     

Synthesis of fused tetrahydropyrans by hydroalkoxylation of δ-hydroxy allenes

Fused tetrahydropyrans were synthesized by silver(I)- and mercury(II)-mediated intramolecular hydroalkoxylations of δ-hydroxy allenes installed on a tetrahydropyran template. Cyclization of simple allenes was promoted by silver perchlorate to afford vinyl-substituted trans-fused bis-tetrahydropyrans, whereas cyclization of methyl-substituted allenes at the internal allenic carbon atom was achieved more effectively with a catalytic amount of mercuric triflate rather than with silver salts.     

Synthesis of Some Novel γ-Spirolactones

Summary. We report on the addition of dialkyl acetylenedicarboxylate to 1-alkylisatins or tryptanthrine in the presence of triphenylphosphine which leads to highly functionalised novel unsaturated -spirolactones.     

A Simple Synthesis of γ-Cyclohomocitral

A simple and efficient synthesis for γ-cyclohomocitral (10), a key and versatile intermediate for the synthesis of some furanosesquiterpenes, is described. The formal total synthesis of (±) Pallenscensone (2) was accomplished.     

Reaction of imidazole and its 2-alkyl derivatives with γ-butyrolactone

Reaction of imidazole with -butyrolactone gives N-alkylation and N-acylation products depending upon the reaction conditions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1491–1493, November, 1992.     

The stable planar conformation of the γ-butyrolactone ring in solution

<正>The conformations ofγ-butyrolactone ring in solution were deduced on the basis of ~1H NMR spectra of geminal protons of the butyrolactone ring.A series of optically pure(Z)-(-)-4-(1'-alkoxyl-1'-carbalkoxy-methylene)-5(R)[(1R)-menthyloxy]-γ-butyr-olactones with a stable planar conformation of γ-butyrolactone ring were found.     

Asymmetric Synthesis of α-Substituted-γ-butyrolactone Empolying Prolinol Type of Auxiliaries

Eleven (S)-(-)-bishydrocarbyl-(l-alkanoylpyrrolidin-2_yl)_methanol derivatives of three types were synthesized from L-proline.asymmtncally selective alkylation products were obtained oy LDA treatment and alkylation using methyl 2-bromoethyl ether, and three types of chiral α-Substituted-γ-butyrolactones were obtained by hydrolyzing the alkylation products, with %e.e. beijing up to 89 percent.     

Access to novel bicyclic fused γ-butyrolactone using [3,3]-sigmatropic rearrangement and acid-lactonization sequence as key transformation

In this Letter, we wish to disclose a new strategy for the construction of substituted γ-butyrolactones. The latter might not only be of potential interest in terms of biological activity and synthesis but also allow access to original heterocyclic scaffolds. According to previous study, efficient two-step sequence involving Eschenmoser-Claisen rearrangement and acid-lactonization reaction was successfully applied for the construction of original fused bicyclic γ-butyrolactones based on an 1,4-oxazine core.     

Synthesis of Secondary α-Methylene γ-Lactams

N-trimethylsilyl aldimines, on reaction with the isolated organozinc derivative of ethyl α-(bromomethyl) acrylate, afford secondary α-methylene γ-lactams with quite quantitative yields.     

Synthesis and Structure of Tetraphenylantimony γ-Alkylacetylacetonates

Tetraphenylantimony -ethylacetylacetonate and -allylacetylacetonate were synthesized by reacting pentaphenylantimony with -ethylacetylacetone or -allylacetylacetone in toluene. Their structures were determined by X-ray diffraction analysis. The coordination polyhedron of the antimony atom is a distorted octahedron. In the tetraphenylantimony -ethylacetylacetonate, the Sb–C bond lengths vary in the 2.156(2)–2.170(1) Å range, the SbOC(1)C(2)C(1")O" heterocycle is symmetric, and the Sb–O and O–C distances are 2.201(1) and 1.284(2) Å, respectively. In the tetraphenylantimony -allylacetylacetonate, the Sb–C bond lengths vary in the 2.159(1)–2.167(1) Å range and the Sb–O(1,2) distances are 2.234(1) and 2.191(1) Å.     

Synthesis and certain transformations of γ-nitrosoalcohols

The -nitrosoalcohols (II), (XII), and (IX), respectively, have been synthesized by acid-catalyzed hydrolysis of 2-alkoxyisoxazolidines (I), (Xa, b), (Xla, b), and 3-(dimethoxyamino)-3-trifluoromethylbutanol-1 (VIII). The nitrosoalcohol (II) readily rearranges into the oxime (III), and (XII) is converted into the diol (XIII) by oxidation with atmospheric O₂ and denitrosation. For (IX) and (XII) ring-chain tautomerism with formation of 2-hydroxyisoxazolidines could not be detected by PMR spectroscopy.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1563–1568, July, 1991.     

Synthesis of β, γ-Unsaturated Valerolactones

In recent years various attempts have been made to use reagent equivalents¹) in order to effect reactions which are not otherwise accessible by means of conventional reagents. Particularly it is to be noted that synthetic equivalents for unreactive dienophiles, such as carbon dioxide,^2,3,4) ketene,^3,5) allene,⁶⁾ and acetylene,⁷⁾ have greatly extended the scope of the cycloaddition reactions into systems not normally generated by the thermal process.     

Apparent molar volumes and compressibilities of electrolytes and ions in γ-butyrolactone

The densities of tetraphenylphosphonium bromide, sodium tetraphenylborate, lithium perchlorate, sodium perchlorate and lithium bromide in γ-butyrolactone at (288.15, 293.15, 298.15, 303.15, 308.15 and 313.15) K and speed of sound at 298.15 K have been measured. From these data apparent molar volumes V_Φ at (288.15, 293.15, 298.15, 303.15, 308.15 and 313.15) K and the apparent molar isentropic compressibility K_S,Φ, at T = 298.15 K of the salts have been determined. The apparent molar volumes and the apparent molar isentropic compressibilities were fitted to the Redlich, Rosenfeld and Mayer equation as well as to the Pitzer and Masson equations yielding infinite dilution data. The obtained limiting values have been used to estimate the ionic data of the standard partial molar volume and the standard partial isentropic compressibility in γ-butyrolactone solutions.