Mass spectra of certain spiro compounds with a central atom of an element of group IVB

Conclusions The mass spectra of 4-silaspiro[3, 3]heptane, 4-silaspiro[3,4]octane, 4-silaspiro[3,5]nonane, as well as spiro[2,3]hexane and spiro[2,4]heptane, were obtained and compared with the known spectra of 4-germaspiro[3,4]octane, 5-stanna- and 5-plumbaspiro[4,4]nonanes, and spiroalkanes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1984–1989, September, 1973.     

An ab initio molecular orbital study of structures and energies of spirocompounds: spiro[3.3]heptane and spiro[3.3]hepta-1,5-diene

Ab initio molecular orbital theory with the STO-3G and 4-31G basis sets is used to determine the equilibrium geometries, enthalpies of formation, strain energies and spiro-interactions for spiro[3.3]heptane and spiro[3.3]hepta -1,5 - diene. For spiro[3.3]heptane, molecular mechanics calculations suggest that the component cyclobutane rings are puckered to a greater extent than in cyclobutane itself. For spiro[3.3]hepta - 1,5 - diene, STO-3G calculations predict that the component cyclobutene rings deviate slightly from an orthogonal arrangement. Spiro-interactions in spiro[3.3]hepta - 1,5 - diene are revealed by comparing the calculated structural parameters and strain energies with those of appropriate reference systems. The π-orbitals in spiro[3.3]hepta -1,5 -diene are predicted to be split by about 0.4 eV.     

Catalytic cyclopropanation of spiro[2.4]hepta-4,6-diene with diazomethane

Catalytic cyclopropanation of spiro[2.4]hepta-4,6-diene with diazomethane in the presence of copper or palladium compounds results in mono- and dicyclopropanation products, namely, spiro[bicyclo[3.1.0]hex-3-ene-2,1′-cyclopropane] and spiro[cyclopropane-1,5′-tricyclo[4.1.0.0^2,4]heptane], with different efficiency. The use of Pd compounds as catalysts allows the cyclopropanation to be performed under conditions of simultaneous generation and decomposition of diazomethane.     

Dzhemilev reaction for the synthesis of spiro[3.3]heptane and spiro[3.4]octanes

For the first time cycloalumination of methylenecyclobutane with the aid of Et₃Al in the presence of Cp₂ZrCl₂ leading to 6-ethyl-6-aluminaspiro[3.4]octane has been realized. The latter, without isolation, was converted into spiro[3.3]heptane, 6-thiaspiro[3.4]octane and also spiro[3.4]octan-6-ol and 6-spiro[3.4]octyl formate with high yields and selectivity.     

Non‐empirical calculations of NMR indirect carbon‐carbon coupling constants. Part 5: Bridged bicycloalkanes

All possible J(C,C) of the bicarbocyclic frameworks together with J(C,H) and J(H,H) at bridgeheads in the series of six bridged bicycloalkanes, bicyclo[1.1.0]butane, bicyclo[2.1.0]pentane, bicyclo[3.1.0]hexane, bicyclo[2.2.0]hexane, bicyclo[3.2.0]heptane and bicyclo[3.3.0]octane, were calculated at the SOPPA level with correlation consistent Dunning sets cc‐pVTZ‐Cs augmented with inner core s‐functions and locally dense Sauer sets aug‐cc‐pVTZ‐J augmented with tight s‐functions and rationalized in terms of the multipath coupling mechanism and hybridization effects explaining many interesting structural trends. Copyright © 2003 John Wiley & Sons, Ltd.     

Preparation of 3,4-fused-spiro[furan-5(5H),4′-piperidin]-2-one

A general method for the preparation of various 3,4-fused-spiro[furan-5(5H),4′-piperidin]-2-one with high yield is reported. The formation of spiro[furanone-piperidine] structure was achieved by a Suzuki coupling, followed by an iodolactonization reaction.     

Highly stereoselective construction of spiro[4.5]decanes by SmI(2)-promoted ketyl radical mediated tandem cyclization

[reaction: see text] Ketyl radical mediated tandem cyclization of omega-alkynyl carbonyl compounds bearing activated alkene using SmI(2) gave spiro[4.5]decanes stereoselectively. In the presence of HMPA, alpha,beta-unsaturated esters and alkenyl phosphonates were converted to spiro[4.5]decanes and a monocyclic compound, respectively. In the presence of Sm, bicyclic lactones were obtained from alpha,beta-unsaturated esters. The spiro[4.5]decane was provided from an alkenyl phosphonate. Interestingly, the stereochemical changeover at the first cyclization has been controlled by means of a variety of activators.     

Synthons for syntheses of spiro[2.4]heptane analogues of prostaglandins

Methods for the preparation of synthons for syntheses of spiro[2.4]heptane analogues of prostaglandins are described. Two of them (1a and1b) enable the syntheses of 11-deoxy-type compounds and were prepared from spiro[2.4]heptan-4-one (3) which after transformation into the 5-phenylthio-,-unsaturated ketone5 was subjected to conjugate addition of organocuprate reagent6. The third synthon (2)-a potential intermediate in syntheses of complete spiro[2.4]heptane analogues of prostaglandins-was prepared from the bicyclic ketone10 byBaeyer-Villiger oxidation followed by epoxidation.

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Ausgangsverbindungen für die Synthese von Prostaglandin-analogen Spiro[2.4]heptanen

Zusammenfassung Es werden Synthesewege für Spiro[2.4]hepane als Analoge zu Prostaglandinen beschrieben. Zwei davon (1a und1b) ermöglichen die Synthese von Verbindungen des 11-Deoxy-Typs; sie wurden aus Spiro[2.4]heptan-4-on (3) dargestellt, das nach der Umwandlung zum 5-phenylthio-,-ungesättigten Keton5 einer konjugierten Addition von Organocuprat-Reagens6 unterworfen wurde. Das dritte (2), ein potentielles Zwischenprodukt in der Synthese von vollständigen Spiro[2.4]heptan-Analogen zu Prostaglandinen, wurde aus dem bicyclischen Keton10 durchBaeyer-Villiger-Oxidation gefolgt von einer Epoxidierung dargestellt.

     

A search for carbene-solvent interactions using time-resolved infrared spectroscopy

[reaction: see text] The time-resolved infrared (TRIR) spectra of chlorophenylcarbene (CPC) and fluorophenylcarbene (FPC) were recorded in heptane at ambient temperature. The C[bond]C and C[bond]F vibrational frequencies involving the carbene carbon were obtained in heptane, benzene, and acetonitrile and in heptane containing 0.1M tetrahydrofuran or benzene. It is concluded that carbene-solvent interactions of CPC and FPC are quite weak.     

A novel bornane synthesis by an old idea

Aiming at a synthesis of spiro[2.4]hepta-4,6-dienes with a carbon substituent at C-4, we investigated solvolysis reactions of the thiatricycle 2, obtained from spiro[2.4]hepta-4,6-diene (1) and thiophosgene by [4 + 2] cycloaddition. With methanol or ethanol a mixture of the esters 7 and 8 was formed. Desulfurization of the thionoesters 8 gave methyl and ethyl spiro[2.4]hepta-4,6-diene-4-carboxylate (10a,b). The corresponding alcohol (11) was prepared from 10b by LiAlH(4) reduction. Ethenetetracarbonitrile combined with the 4-substituted spiro[2.4]hepta-4,6-dienes to give the [4 + 2] cycloadducts 12a-c. Diels-Alder reaction between 11 and 2-chloroacrylonitrile afforded the spiro(bicyclo[2.2.1]hept-5-ene-7,1'-cyclopropane) derivative 14a that was transformed in three steps to rac-10-hydroxycamphor (17). This synthesis of a bornane derivative opens opportunity for variations and thus may find further applications.     

Furans in Synthesis. The Preparation of Spiro-Cyclic Systems.

Furan-terminated cationic cyclizations allylic alcohols, enones, and N-acyl iminium ions as initiators have been explored as routes to highly functionalized spiro[4,5]decanes, spiro[5,5]undecanes, spiro[4,6]undecanes, and spiro[5,6]dodecanes.     

Electronic and Steric Structure of Thermal Isomerization Products of 1-Methyltricyclo[4.1.0.02,7]heptane Radical Cation

Distributions of the positive charge and unpaired electron in stable conformers of the thermal isomerization products of 1-methyltricyclo[4.1.0.02,7]heptane radical cation, having bicyclo[3.1.1]heptane, bicyclo[4.1.0]heptane, bicyclo[3.2.0]hept-6-ene, and 1,3-cycloheptadiene skeletons, were estimated by the PM3 semiempirical method.     

Spirans XVIII . gem-Dialkyl and spirotetrahydrocarbazoles

The reactions of 4,4-dialkylcyclohexanones, spiro[4.5]decan-8-one and various spiro[5.5]-undecanones with phenylhydrazines to produce corresponding 3,3-dialkyltetrahydro and spiro (cycloalkyl 1,n′)-1′,2′,3′,4′-tetrahydrocarbazoles (n = 1, 2 or 3) by the Fischer indole synthesis were examined. Structural assignment of the one isomeric product derived from spiro[5.5]-undecan-2-one was obtained on the basis of pmr spectra.     

Synthesis of Spiro[benzo[h]chromene-4,3′-indoles] and Spiro[benzo[f]chromene-1,3′-indoles]

Russian Journal of Organic Chemistry - New spiro heterocycles, spiro[benzo[h]chromene-4,3′-indoles] and spiro[benzo[f]chromene-1,3′-indoles], have been synthesized in 50–60% yield...     

Spiro[3.3]heptane as a Saturated Benzene Bioisostere**

The spiro[3.3]heptane core, with the non-coplanar exit vectors, was shown to be a saturated benzene bioisostere. This scaffold was incorporated into the anticancer drug sonidegib (instead of the meta-benzene), the anticancer drug vorinostat (instead of the phenyl ring), and the anesthetic drug benzocaine (instead of the para-benzene). The patent-free saturated analogs obtained showed a high potency in the corresponding biological assays.     

Oxidation of some cage hydrocarbons by dioxiranes. Nature of the transition structure for the reaction of C-H bonds with dimethyldioxirane: a comparison of B3PW91 density functional theory with experiment

Dimethyl- (DMD) and methyl(trifluoromethyl)-dioxiranes were used for oxyfunctionalization of spiro{1',7-cyclopropan-(E)-2-methylbicyclo[2.2.1]heptane} (), tricyclo[3.2.2.0(2,4)]nonane (), exo-endo-endo- () and exo-exo-exo- () heptacyclo[9.3.1.0(2,10).0(3,8).0(4,6).0(5,9).0(12,14)]pentadecane, yielding tertiary alcohols as the main products. The rate constants for oxidation of by DMD were measured and the Arrhenius parameters determined. The DFT theory (B3LYP and B3PW91) using restricted and unrestricted methods was employed to study the oxidation reaction of the C-H bond of cage hydrocarbons , adamantane, and acetone with DMD. The kinetic isotopic effect calculated using unrestricted methods agreed with experiment. The reaction mechanism in terms of the concerted oxygen insertion vs. the radical part is discussed.     

Formal (4+1) Cycloaddition and Enantioselective Michael–Henry Cascade Reactions To Synthesize Spiro[4,5]decanes and Spirooxindole Polycycles

Spiro[4,5]decanes and polycyclic compounds bearing spiro[4,5]decane systems are important biofunctional molecules. Described are diastereoselective formal (4+1) cycloaddition reactions to afford oxindole-functionalized spiro[4,5]decanes and organocatalytic enantioselective Michael–Henry cascade reactions of the (4+1) cycloaddition products to generate spirooxindole polycyclic derivatives bearing the spiro[4,5]decane system. Spiro[4,5]decanes bearing oxindoles containing three stereogenic centers and spirooxindole polycycles having seven stereogenic centers, including two all-carbon chiral quaternary centers and one tetrasubstituted chiral carbon center, were obtained with high diastereo- and enantioselectivities.     

Three‐Component Reaction for Construction of Spiro[indoline‐3,7′‐thiazolo[3,2‐a]pyridines] and Spiro[benzo[4,5]thiazolo[3,2‐a]pyridine‐3,3′‐indolines]

The three‐component reaction of thiazole (benzothiazole), dialkyl but‐2‐ynedioate, and isatinylidene malononitriles in toluene at 110–120°C in a sealed tube afforded a mixture of cis/trans‐isomers of functionalized diastereoisomeric spiro[indoline‐3,7′‐thiazolo[3,2‐a]pyridines] and spiro[benzo[4,5]thiazolo[3,2‐a]pyridine‐3,3′‐indolines] in good yields. Both cis‐isomers and trans‐isomers were successfully separated out and fully characterized with spectroscopy and single crystal determination. Under similar conditions, the three‐component reaction containing 2‐(1,3‐dioxo‐1H‐inden‐2(3H)‐ylidene)malononitrile resulted in spiro[indene‐2,7′‐thiazolo[3,2‐a]pyridine] derivatives.     

Photooxygenation of bicyclopropylidene

Upon photooxidation bicyclopropylidene ($\text{1}$) yields spiro[2.3]hexan-4-one ($\text{4}$) and 7-oxatrispiro[2.0.2.1]heptane ($\text{6}$). The formation of these is rationalized. Authentic $\text{6}$ was prepared by epoxidation of $\text{1}$, and $\text{4}$ by isomerization of $\text{6}$.     

[3+2] Cycloaddition of Dimethyl Acetylenedicarboxylate, Methyl Acrylate, and Ethyl Acrylate to 4,5-Dihydro-5-methyl-3H-spiro[benz-2-azepine-3,1'-cyclohexane] N-Oxide

The cycloaddition of methyl acrylate and ethyl acrylate to 4,5-dihydro-5-methyl-3H-spiro[benz-2-azepine-3,1'-cyclohexane] N-oxide proceeds without either regiospecificity or stereospecificity. Eight geometrical isomers of spiro[isoxazolidino[3,2-a]benz-2-azepine-5,1'-cyclohexane] were formed, of which several were isolated as pure samples. The cycloaddition of dimethyl acetylenedicarboxylate proceeds stereoselectively, leading to spiro[isoxazolino[3,2-a]benz-2-azepine-5,1'-cyclohexane] with cis arrangement of the protons at C₍₇₎ and C_(11b).