Novel rearrangement of an isocaryolane sesquiterpenoid under mitsunobu conditions

Under modified Mitsunobu reaction conditions, a novel skeleton rearrangement of terpenes has been obtained. The reactivity of 8, 9-dioxygenated isocaryolane derivatives has been investigated. When either (8R,9R)-8-methoxyisocaryolane-9-ol (7) or (8R, 9R)-isocaryolane-8,9-diol (10) are treated under acidic conditions, isocaryolan-9-one (9) and the rearrangement compound (1S,2S,5R,8S)-1, 4,4-trimethyltricyclo[6.2.1.0(2,5)]undecane-8-carbaldehyde (11) are obtained. Otherwise treatment of compounds 7 and 10 under modified Mitsunobu conditions leads to the novel sesquiterpene derivative (1S, 2S,5R,9R)-1,4,4-trimethyltricyclo[7.2.1.0(2,5)]dodecan-8-one (8). This is the first example, to our knowledge, of a Mitsunobu-induced pinacol rearrangement. The influences of the substrate and reaction conditions on the evolution of the reaction are both explored. This modification of the Mitsunobu reaction conditions introduces a new, one-pot, procedure for preparing this class of rearrangement product.     

Synthesis of novel cage oxaheterocycles

m-CPBA-promoted Baeyer-Villiger oxidation of pentacyclo[6.3.0.0(2,6).0(3,10).0(5,9)]undecan-4-one (1) afforded the corresponding lactone 2 in 93% yield. Lithium aluminum hydride promoted reduction of lactones 2, 6, and 9, performed in the presence of BF(3).OEt(2) reagent, afforded the corresponding cage ethers, i.e., 4, 7, and 10, respectively. Two methods that can be used to replace a cage C=O group by ether oxygen without concomitant rearrangement are delineated. A key step in the first of these methods employs m-CPBA promoted "double Criegee rearrangement", which was used to convert pentacyclo[6.3.0.0(2,6).0(3,10).0(5,9)]undecan-4-one diethyl acetal (11) into 7,9-dioxapentacyclo-[8.3.0.0(2,6).0(3,12).0(5,11)]tridecan-8-one (12). Subsequently, 12 was converted into 4-oxapentacyclo[6.3.0.0(2,6).0(3,10).0(5,9)]undecane (14) via a two-step reduction-dehydration reaction sequence. The second method utilized PhI(OAc)(2)-I(2) reagent to convert cage lactols 15 and 17 into the corresponding cage ethers, i.e., 14 and 2-oxaadamantane (18), respectively.     

Preparation of N'-[2-(5,6-dimethylbenzothiazolyl)]-N-furfuryloxamide with plant growth regulatory activity

The reaction of the N-furfuryloxamic acid sodium salt (12) with 1,1'-oxalyldiimidazole (ODI) yielded the imidazolide (13) as an intermediate, and this directly reacted with 2-aminothiazole derivatives (14) or 2-aminobenzothiazole derivatives (15) under essentially neutral conditions to afford the N'-12-(substituted thiazolyl)]- or N'-[2-(substituted benzothiazolyl)]-N'-furfuryloxamides (6 or 7). The prepared compounds (6 and 7) were examined for plant growth regulatory activity in a seed germination assay. The examination resulted in the discovery of some new revelations that N'-[2-(5,6-dimethylbenzothiazlyl)]-N-furfuryloxamide (7c) at the concentration of 1.0 x 10(-3) M completely inhibited the radicle growth of both rape and leek seedlings.     

Phosphorus-Containing Dendrimers. Easy Access to New Multi-Difunctionalized Macromolecules

Phosphorus-containing dendrimers 1-[G'(1)]-1-[G'(4)] (generation 1 to generation 4) possessing terminal aldehyde groups reacted with a variety of hydrazino compounds. Addition of hydrazine itself to 1-[G'(1)]-1-[G'(4)] afforded the corresponding dendrimers 2-[G(1)]-2-[G(4)] with hydrazono groups at the periphery. Addition of methylhydrazine to 1-[G'(1)], 1-[G'(4)] gave the dendrimers 3-[G(1)], 3-[G(4)]. A Schiff reaction between 1-[G'(1)]-1-[G'(4)] and 1-amino-4-(2-hydroxyethyl)piperazine led to dendrimers 5-[G(1)]-5-[G(4)] possessing up to 48 alcohol chain ends. Treatment of 1-[G'(1)], 1-[G'(3)] with fluorenone hydrazone gave rise to macromolecules 7-[G(1)], 7-[G(3)] while the reaction of 1-[G'(1)], 1-[G'(2)], 1-[G'(4)] with 4-aminobenzo-15-crown-5 afforded the macromolecules 9-[G(1)], 9-[G(2)], 9-[G(4)] in which up to 48 crown ether units are anchored on the surface. Wittig reactions between 1-[G'(1)]-1-[G'(4)] with (acetylmethylene)triphenylphosphorane (10) or (cyanomethylene)triphenylphosphorane (12) allowed the formation of dendrimers 11-[G(1)]-11-[G(4)] or 13-[G(1)], 13-[G(4)] with alpha,beta unsaturated ketones or cinnamonitrile units, respectively, on the surface. Disubstitution of terminal P(S)Cl(2) groups of dendrimers 1-[G(1)]-1-[G(7)] with allylamine, propargylamine, or N-(trimethylsilyl)imidazole easily occurred to give macromolecules 14-[G(1)]-14-[G(7)], 15-[G(1)], 15-[G(4)], 16-[G(1)], 16-[G(4)].     

On triazoles. XXXIII. The reaction of potassium triazolyldithiocarbonates with dihaloalkanes

The reaction of potassium (5-amino-3-Q-1,2,4-triazolyl)dithiocarbonates 2 with 1,ω-dihaloalkanes 7-10 to yield ω-haloalkyldithiocarbonates 11-12 , ω-alkylene-bis(dithiocarbonates) 13-15 and different by-products as the corresponding 7,8-dihydro[1,2,4]triazolo[1,5-c][1,3,5]thiadiazepine-5(9H)-thione ( 16 ), 7,8,9,10-tetrahy-dro[1,2,4]triazolo[1,5-c][1,3,5]thiadiazocine-5-thione ( 17 ) and 1,7-dihydro-5H-1,2,4-triazolo[1,5-c][1,3,5]thiadi-azine-5-thione ( 22 ) derivatives all three representing novel ring systems were obtained. Repeating the reactions with dipotassium salts 3 the corresponding iminodithietans 18 , imino-1,3-dithiolanes 19 and imino-1,3-dithianes 20 were obtained. Unexpectively, the imino-1,3-dithiolanes ( 19 ) rearranged to the corresponding thiazolidines 24-27 under rather mild conditions. A possible mechanism is proposed for this rearrangement.     

1,3-dialkyl- and 1,3-diaryl-3,4,5,6-tetrahydropyrimidin-2-ylidene rhodium(i) and palladium(II) complexes: synthesis, structure, and reactivity

The synthesis of novel 1,3-diaryl- and 1,3-dialkylpyrimidin-2-ylidene-based N-heterocyclic carbenes (NHCs) and their rhodium(i) and palladium(II) complexes is described. The rhodium compounds bromo(cod)[1,3-bis(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene]rhodium (7), bromo(cod)(1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene)rhodium (8) (cod=eta(4)-1,5-cyclooctadiene, mesityl=2,4,6-trimethylphenyl), chloro(cod)(1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene)rhodium (9), and chloro(cod)[1,3-bis(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene]rhodium (10) were prepared by reaction of [[Rh(cod)Cl](2)] with lithium tert-butoxide followed by addition of 1,3-dimesityl-3,4,5,6-tetrahydropyrimidinium bromide (3), 1,3-dimesityl-3,4,5,6-tetrahydropyrimidinium tetrafluoroborate (4), 1,3-di-2-propyl-3,4,5,6-tetrahydropyrimidinium bromide (6), and 1,3-di-2-propyl-3,4,5,6-tetrahydropyrimidinium tetrafluoroborate, respectively. Complex 7 crystallizes in the monoclinic space group P2(1)/n, and 8 in the monoclinic space group P2(1). Complexes 9 and 10 were used for the synthesis of the corresponding dicarbonyl complexes dicarbonylchloro(1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene)rhodium (11), and dicarbonylchloro[1,3-bis(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene]rhodium (12). The wavenumbers nu(CO I)/nu(CO II) for 11 and 12 were used as a quantitative measure for the basicity of the NHC ligand. The values of 2062/1976 and 2063/1982 cm(-1), respectively, indicate that the new NHCs are among the most basic cyclic ligands reported so far. Compounds 3 and 6 were additionally converted to the corresponding cationic silver(i) bis-NHC complexes [Ag(1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene)(2)]AgBr(2) (13) and [Ag[1,3-bis(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene](2)]AgBr(2) (14), which were subsequently used in transmetalation reactions for the synthesis of the corresponding palladium(II) complexes Pd(1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene)(2) (2+)(Ag(2)Br(2)Cl(4) (4-))(1/2) (15) and Pd[1,3-bis(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene)(2)]Cl(2) (16). Complex 15 crystallizes in the monoclinic space group P2(1)/c, and 16 in the monoclinic space group C(2)/c. The catalytic activity of 15 and 16 in Heck-type reactions was studied in detail. Both compounds are highly active in the coupling of aliphatic and aromatic vinyl compounds with aryl bromides and chlorides with turnover numbers (TONs) up to 2000000. Stabilities of 15 and 16 under Heck-couplings conditions were correlated with their molecular structure. Finally, selected kinetic data for these couplings are presented.     

Intramolecular amine-induced [1,3]-sigmatropic rearrangement in the reactions of aminophosphinites or phosphites with elemental sulfur or selenium

Ether- and thioether-functionalized cyclodiphosphazanes cis-[tBuNP(OCH2CH2EMe)]2 (E = O, 1; E = S, 2) react with 2 equiv of elemental sulfur or selenium to produce dichalcogenides cis-[tBuNP(E)(OCH2CH2EMe)]2 (4-6), whereas the similar reaction of amine-functionalized cyclodiphosphazane cis-[tBuNP(OCH2CH2NMe2)]2 (3) with elemental chalcogen results in the formation of thio- or selenophosphates trans-[tBuNP(O)(ECH2CH2NMe2)]2 (E = S, 7; E = Se, 8) through [1,3]-sigmatropic rearrangement. The X-ray crystal structure of 8 confirms the rearranged product as the trans isomer with a planar P2N2 ring. The equimolar reaction of P(OCH2CH2OMe)3 (9) with elemental sulfur or selenium produces the simple sulfide and selenide E=P(OCH2CH2OMe)3 (E = S, 11; E = Se, 12) derivatives, respectively. In contrast, the reaction between P(OCH2CH2NMe2)3 (10) and S or Se furnishes the rearranged products (13 and 14). The rearrangement reaction was monitored by (31)PNMR spectroscopy, which confirms the formation of selenophosphinic acid as the first step of the rearrangement. The [1,3]-sigmatropic rearrangement presumably takes place through chalcogen-nitrogen interactions.     

Development of diversified methods for chemical modification of the 5,6-double bond of uracil derivatives depending on active methylene compounds

The reaction of 5-halogenouracil and uridine derivatives 1 and 7 with active methylene compounds under basic conditions produced diverse and selective C-C bond formation products by virtue of the nature of the carbanions. Three different types of reactions such as the regioselective C-C bond formation at the 5- and 6-positions of uracil and uridine derivatives (products 2, 5, 8, 17, 20 and 21), and the formation of fused heterocycle derivatives 2,4-diazabicyclo[4.1.0]heptane (15) and 2,4-diazabicyclo-[4.1.0]nonane (16) via dual C-C bond formations at both the 5- and 6-positions were due to the different active methylene compounds used as reagents.     

Studies on Organophosphorus Compounds: Synthesis and Reactions of Some New 5′-Cyano-2′-(4-methoxyphenyl)spiro[cycloalkane-1,6′-[1,3,2]thiazaphosphixane]-2′,4′-disulfide Derivatives

2,4-Bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide (Lawesson's Reagent, LR, 1 ) reacts with cycloalkylidenecyanothioacetamides ( 2 and 3 ) to give 5'-cyano-2'-(4-methoxyphenyl)spiro [cyclopentane(cyclohexane)-1,6'-perhydro-[1,3,2]thiazaphosphixane]-2',4'-disulfide ( 4 and 5 ). The reaction of compounds 4 and 5 with f -halo compounds led to the formation of the substituted thio-compounds 6a-e and 7a-e , respectively, these compounds, upon treatment with sodium ethoxide, produce the corresponding thienothiazaphosphixine derivatives 8a-e and 9a-e respectively. Compounds 8a-e and 9a-e react with LR under different reaction conditions to give polyfused heterocyclic compounds 10a-d and 11a-d respectively. Treatment of compounds 8b and 9b with CS 2 and (CH 3 ) 2 SO 4 gave the corresponding dithiocarbamate methyl ester derivatives 12 and 13 , respectively, which on treating with hydrazine hydrate yielded compounds 14 and 15 respectively. Compounds 14 and 15 reacted with LR to yield compounds 16a , b and 17a , b respectively.     

Synthesis and cytotoxic activity of benzo[a]pyrano[3,2-h] and [2,3-i]xanthone analogues of psorospermine, acronycine, and benzo[a]acronycine

Condensation of 2-hydroxy-1-naphthalenecarboxylic acid with phloroglucinol afforded 9,11-dihydroxy-12H-benzo[a]xanthen-12-one (6). Construction of an additional dimethylpyran ring onto this skeleton, by alkylation with 3-chloro-3-methyl-1-butyne followed by Claisen rearrangement, gave access to 6-hydroxy-3,3-dimethyl-3H,7H-benzo[a]pyrano[3,2-h]xanthen-7-one (12) and 5-hydroxy-2,2-dimethyl-2H,6H-benzo[a]pyrano[2,3-i]xanthen-6-one (13), which were methylated into 6-methoxy-3,3-dimethyl-3H,7H-benzo[a]pyrano[3,2-h]xanthen-7-one (14) and 5-methoxy-2,2-dimethyl-2H,6H-benzo[a]pyrano[2,3-i]xanthen-6-one (15), respectively. Osmium tetroxide oxidation of 14 and 15 gave the corresponding (+/-)-cis-diols 16 and 17, which afforded the corresponding esters 18-21 upon acylation. Similarly, condensation of 2-hydroxy-1-naphthalenecarboxylic acid with 3,5-dimethoxyaniline gave 11-amino-9-methoxy-12H-benzo[a]xanthen-12-one (23) which was converted into 11-amino-9-hydroxy-12H-benzo[a]xanthen-12-one (24) upon treatment with hydrogen bromide in acetic acid. Alkylation with 3-chloro-3-methyl-1-butyne followed by Claisen rearrangement afforded 6-amino-3,3-dimethyl-3H,7H-benzo[a]pyrano[3,2-h]xanthen-7-one (25) and 5-amino-2,2-dimethyl-2H,6H-benzo[a]pyrano[2,3-i]xanthen-6-one (26). The new benzopyranoxanthone derivatives only displayed marginal antiproliferative activity when tested against L1210 and KB-3-1 cell lines. The only compounds found significantly active against L1210 cell line, 16 and 20, belong to the benzo[a]pyrano[3,2-h]xanthen-7-one series, which possess a pyran ring fused angularly onto the xanthone basic core.     

Toward stereoselective lactide polymerization catalysts: cationic zinc complexes supported by a chiral phosphinimine scaffold

The P-stereogenic phosphinimine ligands (dbf)MePhP═NAr (7: Ar = Dipp; 8: Ar = Mes; dbf = dibenzofuran, Dipp = 2,6-diisopropylphenyl, Mes = 2,4,6-trimethylphenyl) were synthesized as racemates via reactions of the parent phosphines (rac)-(dbf)MePhP (6) with organoazides. The ligands 7 and 8 were protonated by Br?nsted acids to afford the aminophosphonium borate salts [(7)-H][BAr(4)] (9: Ar = C(6)F(5); 11: Ar = Ph) and [(8)-H][BAr(4)] (10: Ar = C(6)F(5); 12: Ar = Ph). The protonated ligands 9 and 10 were active toward alkane elimination reactions with diethylzinc and ethyl-[methyl-(S)-lactate]zinc to give the heteroleptic complexes [{(dbf)MePhP═NAr}ZnR][B(C(6)F(5))(4)] (Ar = Dipp, 13: R = Et; 15: R = methyl-(S)-lactate; Ar = Mes, 14: R = Et; 16: R = methyl-(S)-lactate). By contrast, reaction of the tetraphenylborate derivative 11 with diethylzinc yielded a phenyl transfer product, [(dbf)MePhP═NDipp]ZnPh(2) (17). Complex 15 was found to catalyze the ring-opening polymerization of rac-lactide.     

Unusual dinuclear and mononuclear cyclometalated iridium complexes of 2,5-diaryl-1,3,4-oxadiazole derivatives

A family of new 2,5-diphenyl-1,3,4-oxadiazole (OXD) derivatives 8-11 bearing ortho-alkyl substituents on one of the phenyl rings is reported. The reactions of these OXDs with IrCl(3) under standard cyclometalating conditions did not give the usual μ-dichloro bridged diiridium OXD complexes. Instead, the novel diiridium complexes 12-14 and the monoiridium complex 15 were isolated and characterized by X-ray crystallography. It is proposed that the unusual structures arise because of the ortho-alkyl substituents leading to a substantial twisting of part of the OXD system which, for steric reasons, changes the normal course of the metal-ligand coordination reactions. Subsequent reactions of 13 and 15 gave the mononuclear complexes 16-18 with acac and picolinate anciliary ligands. The crystal structures of 16 and 18 are reported. Photoluminescence is observed in the green (16) and blue-green regions (17 and 18) at room temperature. Complexes 16-18 are phosphorescent at low temperature, with triplet lifetimes of 4.2-5.7 μs at 77 K.     

Pyrimidine derivatives. VII. Nucleophilic reactions of 5-bromo-1-(bromoalkyl)-6-bromomethyl-2,4(1H,3H)-pyrimidinediones

The reactions of 1-(bromoalkyl)-5-bromo-6-bromomethyl-3-methyl-2,4(1H,3H)-pyrimidinedione (1) with several nucleophiles were examined as follows: by reaction with sodium methoxide, 6-(bismethoxy)methyl-5-debrominated derivatives 2, 3 , and 4 were prepared; the corresponding di-substituted compounds (side chains in 1-and 6-positions) 5, 6, 7 , and 9 were obtained by treatment with silver nitrate, silver acetate, potassium thiocyanate, and potassium thioacetate; the reaction with thioacetamide and iso-butylamine gave bicyclic compounds [1,4]thiazino[4,3-c]- 11 , pyrazino[1,2-c]- 12 , and [1,4]diazepino[1,2-c]pyrimidinedione 13 , respectively; pyrrolidine, morpholine, and sodium azide afforded the corresponding 6-substituted compounds 14, 15 , and 16 .     

Stereochemistry of the macrocyclization and elimination steps in taxadiene biosynthesis through deuterium labeling

Taxadiene synthase catalyzes the cyclization of (E,E,E)-geranylgeranyl diphosphate (GGPP) to taxa-4(5),11(12)-diene (Scheme 1, 5 --> 2) as the first committed step of Taxol biosynthesis. Deuterated GGPPs labeled stereospecifically at C-1, C-4, and C-16 were synthesized and incubated with recombinant taxadiene synthase from Taxus brevifolia to elucidate the stereochemistry of the cyclization reaction at these positions. The deuterium-labeled taxadienes obtained from (R)-[1-(2H1)]-, (S)-[1-(2H1)]-, and [16,16,16-(2H3)]GGPPs (9, 10, and 23b) were established to have deuterium in the 2alpha and 2beta CH2 and 16CH3 positions, respectively, by high-field 1H NMR spectroscopy (eqs 1-3). Incubation of (R)-[4-(2H1)]GGPP (17) with the recombinant enzyme gave a 10:10:80 mixture of [5beta-(2H1)]taxa-3(4),11(12)-diene, [5beta-(2H1)]taxa-4(20),11(12)-diene, and unlabeled taxa-4(5),11(12)-diene according to GC/MS analyses of the products (eq 4). It follows that C-1 of GGPP underwent inversion of configuration, that the A ring cyclization occurs on the si face of C15, and that the terminating proton abstraction removes H5beta from the final taxenyl carbocation intermediate. Thus, the C1-C14 and C15-C10 bonds are formed on the opposite faces of the 14,15 double bond of the substrate, i.e., overall anti electrophilic addition. The implications of these findings for the mechanism of the cyclization and rearrangement are discussed.     

Methylene-bridged glycoluril dimers: synthetic methods

Methylene-bridged glycoluril dimers are the fundamental building blocks of cucurbituril (CB[6]), its homologues (CB[n]), and its derivatives. This paper describes three complementary methods for the synthesis of C- and S-shaped methylene-bridged glycoluril dimers (29-34 and 37-44). For this purpose, we prepared glycoluril derivatives (1a-d) bearing diverse functionalities on their convex face. These glycoluril derivatives were alkylated under basic conditions (DMSO, t-BuOK) with 1,2-bis(halomethyl)aromatics 6-15 to yield 4a-d and 16-24, which contain a single aromatic o-xylylene ring and potentially nucleophilic ureidyl NH groups. Glycoluril derivatives bearing potentially electrophilic cyclic ether groups (5a-f) and 25-28 were prepared by various methods including condensation reactions in refluxing TFA containing paraformaldehyde. The condensation reactions of 4a-d and 16-24 with paraformaldehyde under anhydrous acidic conditions (PTSA, ClCH(2)CH(2)Cl, reflux) give, in most cases, the C-shaped and S-shaped methylene-bridged glycoluril in good to excellent yields. In many cases, the C-shaped compound is formed preferentially with high diastereoselectivity. Cyclic ethers 5a,d-f and 25-26 undergo highly diastereoselective dimerization reactions to yield methylene-bridged glycoluril dimers with the formal extrusion of formaldehyde. Last, it is possible to perform selective heterodimerization reactions using both cyclic ethers and glycoluril derivatives bearing ureidyl NH groups. These reactions deliver the desired C- and S-shaped heterodimers with low to moderate diastereoselectivities. This heterodimerization route is the method of choice in cases where the homodimerization reactions fail. The formation of side products (+/-)-35b and (+/-)-35d helps clarify the electronic requirements for a successful CB[n] synthesis. The X-ray structures of 30C, 38C, and 38S allow for a discussion of the structural features of this class of compounds.     

Cytotoxic diterpenoids from Vietnamese medicinal plant Croton tonkinensis GAGNEP

Six new ent-kaurane-type diterpenoids were isolated from the leaves of the endemic Vietnamese medicinal plant Croton tonkinensis GAGNEP. (Euphorbiaceae) together with three known ent-11alpha-acetoxy-7beta,14alpha-dihydroxykaur-16-en-15-one (1), ent-kaur-16-en-15-one 18-oic acid (5) and ent-18-hydroxykaur-16-ene (7). Their structures were determined by spectroscopic analyses to be ent-7beta-acetoxy-11alpha-hydroxykaur-16-en-15-one (2), ent-18-acetoxy-11alpha-hydroxykaur-16-en-15-one (3), ent-11alpha-acetoxykaur-16-en-18-oic acid (4), ent-15alpha,18-dihydroxykaur-16-ene (6), ent-11alpha,18-diacetoxy-7beta-hydroxykaur-16-en-15-one (8), and ent-(16S)-1alpha,14alpha-diacetoxy-7beta-hydroxy-17-methoxykauran-15-one (14). ent-Kaurane-type diterpenoids from Croton tonkinensis 2-4, 6, and 9-13, were tested for toxicity in the brine shrimp lethality assay. Compounds 9, 10, and 12 demonstrated significant activity, compounds 2, 3, 6, and 11 showed weak activity, and compounds 4 and 13 were inactive.     

A new approach to the synthesis of benzofuro[3,2‐b]quinolines,benzothieno[3,2‐b]quinolines and indolo[3,2‐b]quinolines

Treatment of 2‐hydroxy‐, 2‐mercapto‐, and 2‐ethoxycarbonylamino‐benzonitriles 12 with 2‐fluoro‐ or 2‐nitrophenacylbromides 13 under alkaline conditions provided the corresponding benzofuran, benzothiophene, and indole intermediates 10 , respectivelly. Nucleophilic cyclization of these compounds led to the corresponding tetracyclic quinolinones 7a, 7b , and 3. Denitrocyclization reaction of compounds 10 (R = NO₂) was found especially useful. Compounds 7a, 7b , and 3 were converted to their chloro derivatives 14a‐c , which were reduced with hydrogen and a catalyst to the corresponding compounds 8a, 8b , and 2. The presented pathway represents a new method of preparation of quindoline 2 and its O and S analogs 8. Chloro derivatives 14 are reactive enough to provide the corresponding methoxy derivatives 15 and dimethylamino derivatives 16. Methylation of compounds 7a and 7b with iodomethane providing mixtures of major N‐methyl derivatives 17 and minor O‐methyl derivatives 15 were also studied.     

Studies with polyfunctionally substituted heteroaromatics: A facile route for the synthesis of polyfunctionally substituted N-aminopyridines, 1,2,4-triazolo[1,5-a]pyridines and isoquinolines

The reactions of formaldehyde and acetaldehyde with active methylene compounds, followed by reaction with cyanoacetic acid hydrazide 2, afforded N-aminopyridine-2-one derivatives 5a-f. In contrast, the reactions of cyanoacetic acid hydrazide 2 with aliphatic aldehydes and cyanothioacetamide afforded pyridinethione derivatives 11a-b. Also, the reactions of active methylene compounds with formaldehyde and cyanoacetamide afforded pyridin(1H)-2-one derivatives 12a-c. The reactions of 5b with aldehydes and ketones afforded compounds 13a, b, 14, and 15, respectively. The reactions of 5b with arylidinemalononitriles 16a,b afforded isoquinoline derivatives 19a,b. Compound 19b by hydrolysis gave the final product 20. Compound 20 could also be formed by hydrolysis of 5b to give 21, followed by the reaction with 16b. © 1997 John Wiley & Sons, Inc.     

Diverse closed cavities in condensed rare earth metal-chalcogenide matrixes: Cs[Lu7Q11] and (ClCs6)[RE21Q34] (RE = Dy, Ho; Q = S, Se, Te)

Two types of novel ordered chalcogenids Cs[Lu(7)Q(11)] (Q = S, Se) and (ClCs(6))[RE(21)Q(34)] (RE = Dy, Ho; Q = S, Se, Te) were discovered by high-temperature solid state reactions. The structures were characterized by single-crystal X-ray diffraction data. Cs[Lu(7)Q(11)] crystallize in the orthorhombic Cmca (no. 64) with a = 15.228(4)-15.849(7) ?, b = 13.357(3)-13.858(6) ?, c = 18.777(5)-19.509(8) ?, and Z = 8. (ClCs(6))[RE(21)Q(34)] crystallize in the monoclinic C2/m (no. 12) with a = 17.127(2)-18.868(2) ?, b = 19.489(2)-21.578(9) ?, c = 12.988(9)-14.356(2) ?, β = 128.604(2)-128.738(4)°, and Z = 2. Both types of compounds feature 3D RE-Q network structures that embed with dual tricapped cubes Cs(2)@Se(18) in the former or unprecedented matryoshka nesting doll structure cavities of (ClCs(6))@Se(32) in the latter. The band gap, band structure, as well as a structure change trend of the majority of A/RE/Q compounds are presented.     

Wagner-Meerwein skeletal rearrangement of 3-spiroannulated 6,8a-epoxy- and 6,8a;7,8-diepoxyisoquinolines (3-aza-11-oxatricyclo[6.2.1.0(1,6)]undec-9-enes). Isolation and identification of 5-aza-2-oxatricyclo[6.2.1.0(3,9)]undec-3-enes

The reactions of 3-acetyl-3-aza-11-oxatricyclo[6.2.1.0(1,6)]undec-9-ene and its 9,10-epoxy derivative with bromine and Ac(2)O/BF(3).OEt(2) under different conditions were studied. Unusual products of Wagner-Meerwein rearrangement bearing the olefin fragment (5-aza-2-oxatricyclo[6.2.1.0(3,9)]undecen-3-enes) were isolated and characterized by X-ray analysis.