Palladium-catalyzed cyclization reactions of 3-propargylthio 1,2,4-triazin-5(2h)-ones to thiazolo-1,2,4-triazinones

Selective transformation of 3-propargylthio-1,2,4-triazin-5(2H)-ones ($\text{1}$) to 6-methylene-6,7-dihydro-4H-thiazolo[2,3-c][1,2,4]-triazin-4-ones ($\text{2}$) and 3-methylene-2,3-dihydro-7H-thiazolo[3,2-b]-[1,2,4]triazin-7-ones ($\text{3}$) is performed under the conditions of Pd(II) salt or sodium hydroxide catalysis, respectively.     

Stereochemical studies — 79 synthesis and kinetic study on the retrodiene decomposition of norbornene-condensed 1,3-oxazin-4-ones

The $\text{cis}$-$\text{cxo}$- amino acid $\text{c}$ with norbornene skeleton was converted into 2-aryvl-$\text{cis}$-$\text{cxo}$-1,3-oxazin-4-ones $\text{5a}$-$\text{d}$. These compounds, similarly to the $\text{diendo}$ isomers $\text{1a}$-$\text{d}$ studied by us earlier, undergo retrodiene decomposition under mild conditions to give 2-aryl-6$\text{2}$-l,3-oxazin-6-ones ($\text{2}$$\text{a}$-$\text{d}$) in 50-60% yield. The ratio of the decomposition rate constants of the tricyclic $\text{diendo}$ and $\text{diexo}$-1,3-oxazin-4-ones, measured in toluene solution, is about 2.     

3-methylthio-1,2-dithiolylium salts : Reaction with 4-hydroxy-6-methyl-2H-pyran-2-one and 4-hydroxycoumarin

The reaction of 4- and 5-aryl-3-methylthio-1,2-dithiolylium iodides with 4-hydroxy-6-methyl-2$\text{H}$-pyran-2-one and 4-hydroxycoumarin has been studied. 4-Substituted salts yielded 3-aryl-7-methyl-2-thioxo-2$\text{H}$,5$\text{H}$-pyrano [3,2-c]pyran-5-ones and 3-aryl-2-thioxo-2H,5H-pyrano[3,2-c]benzo[e]pyran-5-ones, respectively, whereas 5-substituted salts gave rise to 3-(5′-aryl-1′,2′-dithiol-3′-ylidene)-6-methyl-2$\text{H}$-pyran-2,4-diones and 3-(5′-aryl-1′,2′-dithiol-3′-ylidene)-2$\text{H}$-benzo [b]-pyran-2,4-diones.     

Reaction des acyloxy-2 chloro-3 chloromethyl-2 propanamides avec l'hydroxyde de potassium ou le fluorure de cesium en milieu heterogene synthese de spiro β-lactames

The reaction of cesium fluoride with the 2-acyloxy 3-chloro 2-chloromethylpropanamides ($\text{4}$) gave the 3-acyloxy 3-chloromethyl azetidine 2-ones ($\text{6}$) . Treated by powdered potassium hydroxide, $\text{4}$ and $\text{6}$ were converted into the 1-oxa 4-oxo 5-aza spiro (2,3) hexanes. These reactions in heterogeneous media were very selective and gave excellent yields.     

The synthesis of regioisomers of dehydroacetic acids

The method for the synthesis of new 2-acyl-6-alkyl(aryl)-3-hydroxy-4H-pyran-4-ones ($\text{3}$), is described, involving the oxidation of 1,3,4,6-tetraketones $\text{1}$ with iodosobenzene diacetate.     

Photochemistry of N-aryl-2(1H)-pyrimidin-2-ones

Irradiation of N-aryl-2(1H)-pyrimidin-2-ones ($\text{3a}$-$\text{c}$) in a mixed benzene-alcohol solution afforded the products initiated by Type I cleavage, 1-(3-alkoxycarbonylamino-2-propene)-N-arylimines ($\text{4a}$-$\text{c}$, $\text{5}$, and $\text{6}$) in 45–51% yields.     

Regiospecific alkylation of tetronic acids : Formation of 4-alkoxy-5H-furan-2-ones and 2-alkoxy-5H-furan-4-ones

2-Alkoxy-5$\text{H}$-furan-4-ones (7,8) and 4-alkoxy-5$\text{H}$-furan-2-ones (4,5) were prepared regiospecifically and in high yields from tetronic acids (4-hydroxy-5$\text{H}$-furan-2-ones) (2) in the first case by acetylating the 4-OH group and then reacting with trialkyloxonium tetrafluoroborate, and in the second case by alkylating tetrabutylammonium tetronates with dialkyl sulfate, respectively. Direct alkylation of tetronic acids with trialkyloxonium tetrafluoroborate gave in four cases regiospecific 2-O-alkylation, in one case 4-O-alkylation and in two other cases mixtures of 2- and 4-alkoxy derivatives.     

Silver(1) ion catalyzed substitution reactions: stereoelectronic control in an SN1 mechanism

Stereochemistry of the acetolysis of 4-, 6α- and 6β-bromocholest-4-en-3-ones using silver acetate was established, and the reactions were interpreted to proceed $\text{via}$ a stereoelectronically controlled S_N1 mechanism.     

Synthesis of oxazolidin-2-ones using carbonate ion on a polymeric support

Through the insertion of a carbon dioxide molecule, the oxazolidin-2-ones ($\text{5a}$) and ($\text{5b}$) were prepared by treataent of the salts ($\text{4a}$) and ($\text{4b}$) with carbonate anion on polymeric support. The hydrolysis under basic conditions of ($\text{5a}$) and ($\text{5b}$) afforded the erythro-3-amino-1,2-diols ($\text{6a}$) and ($\text{6b}$) which were fully acetylated: the 2-amino-2-deoxyerythritol derivative ($\text{7b}$) was obtained in 91% yield.     

Boron trifluoride catalysed reactions of 2,2,2-trichloroethyl 6-diazopenicillanate with aromatic aldehydes: rearrangements via penam c(5)-c(6) bond cleavage.

The BF₃·Et₂O catalysed reactions of diazopenicillanate 1 with aromatic aldehydes provide 2,3-dihydrothiazolo[2,3-b][1,3]oxazin-5-ones 4 $\text{via}$ C(5)-C(6) cleavage of 6-formyl-penicillanates 8.     

Rearrangement during cyclisation of some 3-(2-pyrrolyl) propionic acids and related compounds

Cyclisation of the title compounds leads to mixtures of the expected 4H-cyclopental[b]pyrrol-4-ones (1), the corresponding 6-ones (3) by a single rearrangement, and the cyclopenta[c]pyrrol-4-ones (4) by a double rearrangement, the proportions depending upon the substituents.The ¹H NMR spectra of 2-methyl-4H-cyctopenta[b]thiophen-6-one (3f) shows 6J long range $\text{CH}{}_3\text{CH}{}_2$ coupling, but this is absent in the corresponding pyrroles (3c,d). The ¹³C spectra of 1 and 3 cannot be interpreted on the basis of substituent chemical shifts in pyrroles and thiophens, and are clearly -CH = CH-X (X = NMe, NPh, S) bridged derivatives of cyclopent-2-enone.     

Penicillin-cephalosporin conversion III. A Novel route to 3-chloromethyl-Δ3-cephems

Synthesis of 3-chloromethyl-Δ³-cephems $\text{3}$ from 4-arenesulfonylthioazetidin-2-ones $\text{1}$, derived from penicillins G and V, has been achieved by the electrolytic ene-type chlorination of $\text{1}$ in a CHC1₃-aqueous NaCl-H₂SO₄-(Pt electrodes) system and subsequent ring closure with NH₃ in DMF.     

Stereochemical studies 83 saturated heterocycles 76 : Preparation and conformational study of partially saturated 3,1-benzoxazines, 3,1-benzoxazin-2-ones and 3,1-benzoxazine-2-thiones

The $\text{cis}$- and $\text{trans}$-2-amino-4-cyclohexene-1-carboxylic acids $\text{1}$ and $\text{3}$ react with imidates to give the condensed-skeleton, bicyclic $\text{cis}$- and $\text{trans}$-pyrimidin-4-ones $\text{8}$ and $\text{9}$. The amino acids $\text{1}$ and $\text{3}$ were reduced to the $\text{cis}$-and $\text{trans}$-1, 3-aminoalcohoIs $\text{6}$ and $\text{7}$, which were cyclized by means of imidates to the bicyclic tetrahydro-4$\text{H}$-3,1-benzoxazines $\text{10}$ and $\text{11}$, or were converted, $\text{via}$ the corresponding carbamates $\text{14}$ and $\text{15}$ into the tetrahydro-4$\text{H}$-3,1-benzoxazin-2(1$\text{H}$)-ones $\text{16}$ and $\text{17}$. The 2-thioxo analogues $\text{18}$ and $\text{19}$ were prepared by cyclization of the dithiocarbamates obtained from the aminoalcohols $\text{6}$ and $\text{7}$ by treatment with carbon disulphide. The $\text{trans}$-aminoalcohol $\text{7}$ and its saturated analogue reacted with $\text{p}$-chlorobenzaldehyde to furnish the hexahydro $\text{13}$ and octahydro-4$\text{H}$-3,1-benzoxazine $\text{13a}$, respectively. ¹H and ¹³C NMR studies showed that, similarly to the earlier-investigated analogues containing oxygen or unsubstituted nitrogen at position 1, the synthesized $\text{cis}$ isomrs $\text{8}$, $\text{10}$, $\text{16}$ and $\text{18}$ occurred as the preferred conformer in the heterocyclic twist inverse form of $\text{N}$-inside type ($\text{quasiaxial}$ C₆-N bond) (B). In the $\text{trans}$ isomers containing a saturated C-2 atom ($\text{13}$ and $\text{13a}$), H-2 and H-6 are in $\text{cis}$ relative positions.     

A synthetic approach to (+)-aldosterone and its relatives (2)- a stereoselective synthesis of (+)-trans-4,5-(4-methoxybenzo)- 1β , 7aβ - ( 2α-methoxymethyl- 5 -oxofuro) hydrindane

A stereoselectivity in an intramolecular cycloaddition of the olefinic $\text{o}$-quinodimethanes 13 and 23 generated $\text{in}$$\text{situ}$ from the thermolysis of optically active 4β-[2-(4-methoxybenzocyclobutenyl)ethyl] -5α-methoxymethyl-3-phenyl-thio-methylenefuran-2-ones 12 and 22, respectively, is studied and a stereoselective synthesis of (+)-$\text{trans}$-4,5-( 4-methoxybenzo) -1β,7aβ-(2α-methoxymethyl-5-oxofuro)hydrindane 1 is also described.     

Syntheses and reactions of 1,2-dihydrocyclobuta[c]isoquinolin-4(3H)-ones

Two-step synthesis of 1,2-dihydrocyclobuta[$\text{c}$]isoquinolin-4(3H)-ones, novel cyclobutane-fused heterocycles, from 3-methoxy-2-methylisoquinolin-1(2H)-one and their reacion with olefins are described.     

Synthesis of Bicyclo[2.2.1]heptan-2-ones by thermal cyclization of 3-allylcyclopentanones

Pyrolysis of 3-allylcyclopentanones affords $\text{endo}$-6-substituted bicyclo[2.2.1]heptan-2-ones.     

A new route to 7-deazaguanine derivatives

The Synthesis of 2-amino-4,6-dichloro-5-(2,2-diethoxyethyl) pyrimidine $\text{7}$ has been performed in four steps starting from guanidine and diethylallylmalonate. $\text{7}$ is a new key intermediate for the synthesis of 7-alkyl-2-amino-3,4-dihydro-7H-pyrrolo [2,3-d] pyrimidin-4-ones.     

Reactions of o-tolyl isocyanide with isocyanate and isothiocyanate syntheses of n-substituted indole-3-carboxamides and indole-3-thiocarboxamides

o-Lithomethylphenyl isocyanide is reacted at ?78° with isocyanates and isothiocyanates to produce o-isocyanophenyl-acetamides $\text{(2a)}$ and -acetothioamides $\text{(2b)}$. Isocyanides $\text{(2a)}$ and $\text{(2b)}$ are cyclized to indole-3-carboxamides $\text{(3a)}$ and -3-thiocarboxamides $\text{(3b)}$ via lithiathion, respectively. Isocyanides $\text{2a}$ are also cyclized by Cu₂O catalyst to produce 4,5-dihydro-1,3-benzodiazepin-4-ones $\text{(4a)}$ with $\text{(3a)}$.     

Reactivite des β-cyclopropyl α-enones—I: Etude des transferts electroniques par voltametrie cyclique et de la reduction par l'electron solvate dans l'ammoniac liquide

Species produced by electron transfer to variously substituted bicyclo[3.1.0]hex-3-en-2-ones provide a better insight into the origin of 1,6-addition products sometimes observed by reaction of lithium diorganocuprates with β-cyclopropyl α-enones. Cyclic voltammetry of eight such bicyclohexenones show that the half-lives of the corresponding anion radicals are very short (t_{$\text{1}\text{2}$}?10^?4s) except when the initial molecule is phenyl substituted at C-4. In such cases the anion radicals are very stable (t_{$\text{1}\text{2}$}?6s) owing to the greater charge delocalization and we observe a second wave corresponding to the formation of the Dianion. The reduction of the same substrates by the solvated electron in liquid ammonia exhibits the same difference of behaviour. The molecules giving strongly reactive anion radicals only lead to the straight-forward product expected by conjugate reduction; while the 4-phenyl substituted substrates yield a mixture of products from normal conjugate reduction and rearrangement. This correlation strongly suggest that these last products arise from the rearrangement of the dianion.     

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.