Ene-type reaction of trisubstituted monoterpene alkenes with methyl sulfite and thionyl chloride

Trisubstituted methylalkenes react with methyl sulfite at 25°C in the presence of BF₃ · Et₂O in the ene-type fashion to give the corresponding methallyl sulfinates. Such compounds can also be prepared under considerably milder conditions by the Et₂AlCl-catalyzed reaction of thionyl chloride with mono- and dienes followed by methanolysis of intermediate alkyl sulfinyl chlorides. These reactions represent a new method for terminal functionalization of linear isoprenoids.Deceased Nov.1, 1992.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 105–107, January, 1993.     

Radical [3 + 2] cycloaddition reaction with various alkenes using iodomethylcyclopropane derivatives as new homoallyl radical precursors

Radical iodine atom transfer [3 + 2] cycloaddition with various alkenes using dimethyl 2-(iodomethyl)cyclopropane-1,1-dicarboxylate and 1,1-bis(phenylsulfonyl)-2-(iodomethyl)cyclopropane as new precursors of a homoallyl radical species smoothly proceeds to give functionalized cyclopentane derivatives in good yields.     

Base-promoted reaction of methyl 4,6-O-benzylidene-3-deoxy-hexopyranosid-2-ulose and various arylamines

Reaction of methyl 4,6-O-benzylidene-3(2)-deoxy-hexopyranosid-2(3)-ulose (1) with various arylamines under Bargellini reaction conditions was investigated. A series of unique enaminoketones 3-12 was obtained unexpectedly under basic conditions in 52-72% yield.     

Synthesis of N-methylmorpholinium 6-methyl-4-(2-thienyl)-5-phenylcarbamoyl-3-cyano-1,4-dihydropyridine-2-thiolate and its reaction with various functionally substituted methyl halides

Condensation of the anilide of acetoacetic acid, thiophene aldehyde, cyanothioacetamide and N-methyl-morpholine gave N-methylmorpholinium 6-methyl-4-(2-thienyl)-5-phenylcarbamoyl-3-cyano-1,4-dihydropyridine-2-thiolate which reacted with various halides ZCH₂Hal or H₂NCOCH(Ph)Cl to give substituted 2-ZCH₂-thio or 2-H₂NCOCH(Ph)-thio-1,4-dihydropyridines.     

2+2] Photocycloaddition reaction dynamics of triplet pyrimidines

Taking the 266 nm excited pyrimidine (uracil or thymine) with cyclopentene as model reaction systems, we have examined the photoproduct formation dynamics from the [2 + 2] photocycloaddition reactions of triplet pyrimidines in solution and provided mechanistic insights into this important DNA photodamage reaction. By combining two compliment methods of nanosecond time-resolved transient IR and UV-vis laser flash-photolysis spectroscopy, the photoproduct formation dynamics as well as the triplet quenching kinetics are measured. Characteristic IR absorption bands due to photoproduct formation have been observed and product quantum yields are determined to be ～0.91% for uracil and ～0.41% for thymine. Compared to the measured large quenching rate constants of triplet uracil (1.5 × 10(9) M(-1)s(-1)) or thymine (0.6 × 10(9) M(-1)s(-1)) by cyclopentene, the inefficiency in formation of photoproducts indicates competitive physical quenching processes may exist on the route leading to photoproducts, resulting in very small product yields eventually. Such an energy wasting process is found to be resulted from T(1)/S(0) surface crossings by the hybrid density functional calculations, which compliments the experiments and reveals the reaction mechanism.     

Gas phase reaction of NO2 with alkenes and dialkenes

The kinetics of the gas phase reactions of NO₂ with a series of organics have been studied at 295 ± 2 K. It was observed that only 2,3-dimethyl-2-butene and the conjugated dialkenes studied reacted at observable rates, with rate constants which ranged from 1.5 × 10^?20 cm³ molecule^?1 s^?1 for 2,3-dimethyl-2-butene to 1.3 × 10^?17 cm³ molecule^?1 s^?1 for α-phellandrene. These rate constants are compared with the available literature data and the mechanisms of these reactions are discussed.     

Generation and reaction of tungsten-containing carbonyl ylides: [3 + 2]-cycloaddition reaction with electron-rich alkenes

Novel tungsten-containing carbonyl ylides 7, generated by the reaction of the o-alkynylphenyl carbonyl derivatives 1 with a catalytic amount of W(CO)(5)(thf), reacted with alkenes to give polycyclic compounds 5 through [3 + 2]-cycloaddition reaction followed by intramolecular C-H insertion of the produced nonstabilized carbene complex intermediates 8. In the presence of triethylsilane, these tungsten-containing carbene intermediates 8 were smoothly trapped intermolecularly by triethylsilane to give silicon-containing cycloadducts 17 with regeneration of the W(CO)(5) species. By this procedure, the scope of alkenes employable for this reaction was clarified. The presence of the tungsten-containing carbonyl ylide 7c was confirmed by direct observation of the mixture of o-ethynylphenyl ketone 1c and W(CO)(5)(thf-d(8)). Careful analysis of the intermediate by 2D NMR, along with the observation of the direct coupling with tungsten-183 employing the (13)C-labeled substrate, confirmed the structure of the ylide 7c. Examination using (E)- or (Z)- vinyl ether revealed that the [3 + 2]-cycloaddition reaction proceeded in a concerted manner and that the facial selectivity of the reaction differed considerably depending on the presence or absence of triethylsilane. These results clarified the reversible nature of this [3 + 2]-cycloaddition reaction.     

Synthesis of Indole Derivatives by [2 + 2] Photocycloaddition of Indoline-2-thiones with alkenes and photodesulfurization of indoline-2-thiones

The photochemical synthesis of indole derivatives starting from the indoline-2-thiones 1 is described. Irradiation of indoline-2-thiones 1 in the presence of alkenes 3 gave 2-alkyl-3H-indoles 4 – 7 or 2-alkylindoles 8 – 22 through the ring cleavage of the intermediates, spirocyclic amino-thietanes, initially derived by [2 + 2] cycloaddition of the C?S bond of 1 and the C?C bond of 3 . Irradiation of 1 in the presence of trialkylamines 26 gave desulfurization products 27 – 32 and unexpected 3-alkylindoles 33 – 40 . N-Acylindoline-2-thiones 11 - p yielded the deacylated products, indoline-2-thiones 1a - b , and ethyl esters 43 through γ-H abstraction by the excited thioamide S-atom when irradiated in CDC1₃/EtOH or benzene/EtOH. Oxygen analogues 2a - d also underwent intramolecular H abstraction to give the indolin-2-ones 2e – f and ethyl esters 43 in a similar way.     

Novel Photocycloaddition Reactions of N-Methyl-2, 3-naphthalenedicarboximide with Phenylacetylene

UV irradiation of N-methyl-2,3-naphthalenedicarboximide with phenylacetylene in benzene solution afforded a novel hexacyclic adduct 2 confirmed unambiguously by single crystal X-ray diffraction.     

Palladium-induced electron-transfer reaction of difluorodiiodomethane with alkenes

The addition reaction of difluorodiiodomethane (1) with alkenes in the presence of PdCl2(PPh3)2 or Pd(PPh3)4 afforded the corresponding iododifluoromethylated compounds in excellent yield.     

The reaction of methyl propiolate with 2-aminopyridines

The structure (III) reported by Lappin (2) for the diadducts formed by the reaction of methyl propiolate with 2-aminopyridines has been found to be incorrect. The correct structure (IV) has been proven by spectral studies and cyclisation to compound VII. In two cases new compounds having structures of the type (III) have been isolated. N.M.R. data are reported for all products.     

A highly stereoselective synthesis of aldols employing the Reformatsky reaction of 3-(2-bromopropionyl)-2-oxazolidone derivatives with various aldehydes

The title reactions of sterically crowded 2-oxazolidone derivatives with achiral aldehydes in the presence of zinc dust were found to give various 2,3- -aldols as major products (at most, 2,3- :2,3- =98:2). While a 2,3- -3,4- -aldol could be similarly produced in a highly stereoselective manner, application of the explored reaction to asymmetric synthesis of optically active 2,3- -aldols was found to be unpromising.     

Zirconium-catalyzed reaction of terminal alkenes with triethylindium

Terminal alkenes (undec-1-ene, oct-1-ene, and allylbenzene) reacted with triethylindium in the presence of a catalytic amount of Cp₂ZrCl₂ in hexane to give mixtures of three organoindium compounds whose hydrolysis in D₂O afforded 2-substituted 1,4-dideuterobutane containing minor amounts of 2-substituted 1- and 4-deuterobutanes.     

Photocycloaddition of 2-Oxopyran-3-carbonitriles to 2,3-Dimethylbut-2-ene

On acetone-sensitized irradiation in the presence of 2,3-dimethylbut-2-ene, α-cyano-α,β-unsaturated δ-lactone 5 is converted both to cyclopentapyrans resulting from stepwise addition of the alkene to the olefinic C(β)- and the nitrile C-atom of triplet excited 5 , and cyclobutapyranes, i.e., [2+2] cycloadducts. Similarly, direct irradiation of 1-benzopyran-3-carbonitrile 6 in the presence of the same alkene affords cyclobutabenzopyran 13 and cyclopentabenzopyran 14 , the latter resulting from an upper excited triplet state of 6 .     

Photocycloaddition of 2-Cyanocycloalk-2-Enones to 2, 3-Dimethylbut-2-Ene

Irradiation of 5,5-dimethyl-6-oxocyclohex- l-ene- l-carbonitrile ( 1 ) in the presence of 2,3-dimethylbut-2-ene afforded 3,3,4,4,7,7-hexamethyl-3,4,4a,5,6,7-hexahydroindeno[1,7-c,d]-],2-oxazole (3) in nearly quantitative yield. In contrast, 4,4-dimethyl-5-oxo-cyclopent-l-ene-l-carbonitrile ( 2 ) under the same conditions reacted not to a tricyclic isoxazole but to a 2:1 mixture of 3,3,6,6,7,7-hexamethyl-2-oxo-bicyclo[3.2.0]heptane-l-carbonitrile ( 4 ) and trans-3,3-dimethyl-2-oxo-5-(2,3-dimethylbut-3-en-2-yl)cyclopentane-l-carbonitrile ( 5 ), respectively.     

Reformatsky reaction of methyl 1-bromocyclohexane-1-carboxylate with N-aryl-2-oxochromene-3-carboxamides

Reformatsky reagent generated from methyl 1-bromocyclohexane-1-carboxylate reacted with N-aryl-2-oxochromene-3-carboxamides and N-aryl-6-bromo-2-oxochromene-3-carboxamides to give, depending on the conditions, the corresponding N-aryl-(6-bromo)-4-(1-methoxycarbonylcyclohexyl)-2-oxochroman-3-carboxamides or 3-aryl-(9-bromo)-1,1-pentamethylene-2,3,4,4a,5,10b-hexahydro-1H-chromeno[3,4-c]pyridine-2,4,5-triones. The products were isolated as a single diastereoisomer.     

Palladium-catalyzed reaction of phenyl fluoroalkanesulfonates with alkynes and alkenes

Palladium-catalyzed reaction of phenyl fluoroalkanesulfonates with alkynes and alkens under mild conditions gives the corresponding alkynyl and alkenyl substituted benzenes in good yields.