1‐Oxa‐nido‐dodecaborate [OB11H12]− from the Controlled Oxidation of the closo‐Borates [B11H11]2− and [B12H12]2−

The closo‐dodecaborate [B₁₂H₁₂]^2? is degraded at room temperature by oxygen in an acidic aqueous solution in the course of several weeks to give B(OH)₃. The degradation is induced by Ag²⁺ ions, generated from Ag⁺ by the action of H₂S₂O₈. Oxa‐nido‐dodecaborate(1?) is an intermediate anion, that can be separated from the reaction mixture as [NBzlEt₃][OB₁₁H₁₂] after five days in a yield of 18 %. The action of FeCl₃ on the closo‐undecaborate [B₁₁H₁₁]^2? in an aqueous solution gives either [B₂₂H₂₂]^2? (by fusion) or nido‐B₁₁H₁₃(OH)^? (by protonation and hydration), depending on the concentration of FeCl₃. In acetonitrile, however, [B₁₁H₁₁]^2? is transformed into [OB₁₁H₁₂]^? by Fe³⁺ and oxygen. The radical anions [B₁₂H₁₂] ^{˙ ?} and [B₁₁H₁₁] ^{˙ ?} are assumed to be the primary products of the oxidation with the one‐electron oxidants Ag²⁺ and Fe³⁺, respectively. These radical anions are subsequently transformed into [OB₁₁H₁₂]^? by oxygen. The crystal structure analysis shows that the structure of [OB₁₁H₁₂]^? is derived from the hypothetical closo‐oxaborane OB₁₂H₁₂ by removal of the B3 vertex, leaving a non‐planar pentagonal aperture with a three‐coordinate O vertex, as predicted by NMR spectra and theory.     

Diphosphapodanden, [12]‐, [15]‐ und [18]Diphosphacoronanden,Diphosphacryptand‐8 und Alkalimetall‐Komplexe

Diphosphapodands, [12]‐, [15]‐, and [18]Diphosphacoronands, Diphosphacryptand‐8, and Alkali‐Metal Complexes The cyclizing bis‐phosphonium‐salt formation of the open‐chain bis‐phosphine 17a (1,1,7,7‐tetrabenzyl〈P.O.P‐podand‐7〉) with diethylene glycol derived dibromide 13a yields the 12‐membered cyclic bis‐phosphonium salt 20 (4,4,10,10‐tetrabenzyl‐12〈O.P.O.P‐coronand‐4〉‐4,10‐diium dibromide) in yields as high as 50–60%. The 1,1,10,10‐tetrabenzyl〈P.O₂.P‐podand‐10〉 17b forms with 13a the 15‐membered cyclic bis‐phosphonium salt 21 (7,7,13,13‐tetrabenzyl‐15〈O₂.P.O.P‐coronand‐5〉‐7,13‐diium dibromide) with the same high yield. By quaternization of the bis‐phosphine 17b with triethylene glycol derived dibromide 13b , the 18‐membered 7,7,16,16‐tetrabenzyl‐18〈O₂.P.O₂.P‐coronand‐6〉‐7,16‐diium dibromide 24 is obtained in 50% yield, too. The Wittig reaction of the cyclic phosphonium salts with benzaldehyde yields the 12‐, 15‐, and 18‐membered cyclic bis‐benzylphosphine dioxides 9, 10 , and 11 as cis‐ and trans‐isomers beside trans‐stilbene. The 7,13‐dioxido‐7,13‐dibenzyl‐15〈O₂.P.O₂.P‐coronand‐5〉 10 forms a crystalline 1 : 1 Na‐complex 23 , which exists as a dimer. The structure of 23 was established by an X‐ray analysis and spectroscopic data. The 7,16‐dibenzyl‐18〈O₂.P.O₂.P‐coronand‐6〉 28 that is available by reduction of 11 with CeCl₃/LiAlH₄ reacts with triethylene glycol derived dibromide 13b under Ruggly Ziegler‐dilution conditions to give the bicyclic bis‐phosphonium salt 29 (1,10‐dibenzyl〈P[O₂]₃.P‐cryptand‐8〉‐1,10‐diium dibromide) in 18% yield. Again, by the Wittig procedure with benzaldehyde, the 7,16‐dioxido〈P[O₂]₃P‐cryptand‐8〉 12 is obtained as the first diphosphacryptand. The FD‐MS (CH₂Cl₂) of the cyclic bis‐phosphine dioxides 10 – 12 show that they exist as [2M+Na]⁺ complexes. The complex formation constants K_a of 9 – 11 with alkali‐metal cations are studied and compared with the complex formation of corresponding crown ethers.     

Polycyclic N‐Heterocyclic Compounds. Part 75: Synthesis of 2,4‐Disubstituted 5,6‐dihydro[1]benzoxepino[5,4‐d]pyrimidines and 12‐Substituted 1,2,4,5‐Tetrahydro[1]benzoxepino[4,5‐e]imidazo[1,2‐c]pyrimidines as Potential Antiplatelet Aggregators

Libraries of tricyclic 2‐substituted 4‐alkylamino‐5,6‐dihydro[1]benzoxepino[5,4‐d]pyrimidines and tetracyclic 12‐substituted 1,2,4,5‐tetrahydro[1]benzoxepino[4,5‐e]imidazo[1,2‐c]pyrimidines were synthesized as part of our research to develop new effective antiplatelet drugs. Several alkyl and aryl groups were used as substituents at the 2‐position. Evaluation of the effects of the newly synthesized compounds on collagen‐induced platelet aggregation revealed several promising antiplatelet candidates with potencies superior to aspirin.     

Synthesis of 1,4,5,6‐tetrahydropyrazolo[3,4‐d]pyrido[3,2‐b]azepine

The synthesis of 7,8‐dihydro‐5(6H)‐quinolinone ( 3 ) from commercially available 3‐amino‐2‐cyclohexen‐1‐one ( 1 ) and 3‐(dimethylamino)acrolein ( 4 ) in 23% yield avoids the preparation of propynal ( 2 ). Conversion of 5‐(4‐methylphenylsulfonyl)‐6,7,8,9‐tetrahydro‐5H‐pyrido[3,2‐b]azepine ( 12 ) to 6‐(4‐methylphenylsulfonyl)‐1,4,5,6‐tetrahydropyrazolo[3,4‐d]pyrido[3,2‐b]azepine ( 24 ) is described. Removal of the N‐(4‐methylphenylsulfonyl) group with 40% sulfuric acid in acetic acid gave the tricyclic azepine 26. Application of a similar series of reactions to 5‐(4‐nitrobenzoyl)‐6,7,8,9‐tetrahydro‐5H‐pyrido[3,2‐b]‐azepine ( 13 ) afforded 6‐(4‐nitrobenzoyl)‐1,4,5,6‐tetrahydropyrazolo[3,4‐d]pyrido[3,2‐b]azepine ( 25 ).     

On the chemistry of 5‐aryl‐2‐hydrazino‐benzo[6,7]cyclohepta[1,2‐b]pyrido[2,3‐e] pyrimidin‐4‐one

Several pyrido[2,3‐e]pyrimidine fused with other rings have been prepared by intramolecular cyclization of 5‐(4‐chlorophenyl)‐2‐hydrazino‐benzo [6,7]cyclohepta‐[1,2‐b]pyrido[2,3‐e]pyrimidine‐4‐one ( 1 ) with acids, carbon disulfide to form triazole derivatives ( 2,4 ), halo‐ketones to give triazine derivative ( 5 ), β‐ketoesters, β‐cyanoesters, and β‐diketones to yield 2‐(1‐pyrazolyl) derivatives ( 7,9,10 ), and aldehydes to form arylhydrazone derivatives ( 11a,b ) which cyclized to form triazoles ( 12a,b ). Also, acyclic N‐nucleosides are prepared by heating under reflux 2‐hydrazino‐benzo[6,7]cyclohepta[1,2‐b]pyrido[2,3‐e] pyrimidin‐4‐one ( 1 ) with xylose and glucose to give the corresponding acyclic N‐nucleosides ( 13a,b ) which are cyclized to afford the corresponding protected tetra and penta–O‐acetate C‐nucleosides ( 14a,b ). Deacetylating of the latter nucleosides afforded the free acyclic C‐nucleosides ( 15a,b ). © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:34–43, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20248     

Synthesis of 1,2,3,12a,12b‐Hexahydrocyclopropa‐[1,2‐d]benzo[f]pyrrolo[1,2‐b]isoquinolin‐5,7‐dione related to duocarmycins and anthramycin

Structural features of the Duocarmycins and Anthramycin were incorporated into 1,2,3,12a,12b‐hexahydro‐cyclopropa[1,2‐d]benzo[f]pyrrolo[1,2‐b]isoquinolin 5,7‐dione. The synthesis of the cis and trans diastereomers was accomplished using a benzyne Diels‐Alder reaction and an imine‐anhydride cyclization as key steps.     

Methanesulfonic Acid‐Catalyzed One‐Pot Synthesis of 12‐Aryl or 12‐Alkyl‐8,9,10,12‐tetrahydrobenzo[a]xanthen‐11‐one Derivatives

An efficient synthesis of 12‐aryl or 12‐alkyl‐8,9,10,12‐tetrahydrobenzo[a]xanthen‐11‐one derivatives has been developed under solvent‐free conditions by one‐pot condensation of aldehydes, 2‐naphthol, and cyclic 1,3‐dicarbonyl compounds in the presence of a catalytic amount of methanesulfonic acid. The protocol has advantages of mild condition, short reaction time, high yield, and operational simplicity.     

Spiro[pyrido[3,2,1‐ij]pyrimido[4,5‐b]quinoline‐7,5′‐pyrrolo[2,3‐d]pyrimidines] and Spiro[pyrimido[4,5‐b]quinoline‐5,1′‐pyrrolo[3,2,1‐ij]quinolines] Derived from 5,6‐Dihydro‐4H‐pyrrolo[3,2,1‐ij]quinoline‐1,2‐dione

Reaction of 5,6‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinoline‐1,2‐dione ( 1 ) with two equivalents of some 6‐aminouracils (or 6‐amino‐2‐thiouracil) generates spirocyclic tetrahydrobenzo[if]quinolizines ( 7 ). The one‐pot, three‐component reaction of amido ketone ( 1 ) with 6‐aminouracil (or 6‐amino‐2‐thiouracil) and a cyclic six‐membered 1,3‐diketone produces spirocyclic tetrahydropyrrolo[3,2,1‐ij]quinolinones ( 15 ).     

Synthesis of Novel 6‐Mercapto‐12‐phenethyl‐quinazolino[3,4‐a]quinazolinones

Novel 6‐mercapto‐12‐phenethyl‐quinazolino[3,4‐a]quinazolinone derivatives were synthesized through a user‐friendly five‐step reaction starting from isatoic anhydride. All products were characterized by IR, ¹H‐NMR, ¹³C‐NMR spectroscopy, and chemical analysis. All of them were evaluated for their in vitro cytotoxic activity against two cell lines namely MOLT‐4 (human lymphoblastic leukemia) and MCF‐7 (human breast adenocarcinoma).     

Dodecahydro‐closo‐undecaborate [B11H12]–

DFT‐calculations of the geometries of the closo‐anion [B₁₁H₁₁]^2– in its ground state and in the transition state of its skeletal rearrangement and of the protonated species [B₁₁H₁₂]^– in its ground state were performed at the B3LYP/6‐31++G(d,p) level. The corresponding NMR shifts were computed on the basis of the optimized geometry by the GIAO method at the same level. Calculated and observed NMR data are in good agreement and thus prove the structure of [B₁₁H₁₂]^–, previously deduced from 2 D‐NMR spectra. The addition of water, ethanol, and pyridine to [B₁₁H₁₂]^– at low temperature gave the nido‐species [B₁₁H₁₃(OH)]^–, [B₁₁H₁₃(OEt)]^–, and [B₁₁H₁₂(py)]^–, respectively. The structures of these anions were investigated by NMR methods and the last two of them by crystal structure analyses of appropriate salts. The course of the addition reactions can be rationalized on the basis of the structurally characterized reaction components.     

Azinoiminophosphorane mediated 4H,8H‐1,2,4‐triazolo[1,5‐C]‐[1,3]oxazepin‐4‐ones and 5,6‐dihydro‐7H, 12H‐naphtho[2,1‐f]‐[1,2,4]triazolo[1,5‐c][1,3]oxazepin‐7‐ones synthesis

The aza‐Wittig reactions of benzaldehyde‐, acetophenone‐ and benzophenone 1‐[(triphenylphosphor‐anylidene)amino]ethylidenehydrazones ( 1 ) with 2,3‐furandiones 6 provide a new route to 4H,8H‐1,2,4‐triazolo[1,5‐c][1,3]oxazepin‐4‐ones 14 or 5,6‐dihydro‐7H,12H‐naphtho[2,1‐f|[1,2,4]triazolo[1,5‐c]‐[1,3]oxazepin‐7‐ones 17 via the thermal reaction of the expected azinoimine vinylogous lactones.     

Reactions of hydrazonoyl halides 43 : Synthesis of some new 2,3‐dihydro‐1,3,4‐thiadiazoles,pyrazoles, pyrazolo[3,4‐d]‐pyridazines,thieno[2,3‐b]pyridines,pyrimidino[4′,5′:4,5]thieno[2,3‐b]‐pyridines and pyrrolo[3,4‐d]pyrazoles

2,3‐Dihydro‐1,3,4‐thiadiazoles, pyrazoles, pyrazolo[3,4‐d]pyridazines, thieno[2,3‐b]pyridines, pyrim‐idino[4′,5′:4,5]thieno[2,3‐b]pyridines and pyrrolo[3,4‐d]pyrazoles were obtained in a good yields by treatment of hydrazonoyl halides with each of alkyl carbodithioates, 3‐(dimethylamino)‐1‐naphtho[1,2‐d]furan‐2‐ylprop‐2‐en‐1‐one and N‐arylmalemides.     

Synthesis and Characterization of 11‐Amino‐3‐methoxy‐8‐substituted‐12‐aryl‐8,9‐dihydro‐7H‐chromeno[2,3‐b]quinolin‐10(12H)‐one Derivatives

A series of 2‐amino‐7‐methoxy‐4‐aryl‐4H‐chromene‐3‐carbonitrile compounds 2 were obtained by condensation of 3‐methoxyphenol with β‐dicyanostyrenes 1 in absolute ethanol containing piperidine. The intermediate enamines 3 were prepared by compounds 2 with 5‐substituted‐1,3‐cyclohexanedione using p‐toluenesuflonic acid (TsOH) as catalyst. The title compounds 11‐amino‐3‐methoxy‐8‐substituted‐12‐aryl‐8,9‐dihydro‐7H‐chromeno[2,3‐b]quinolin‐10(12H)‐one 4 were synthesized by cyclization of the intermediate enamines 3 in THF with K₂CO₃ /Cu₂Cl₂ as catalyst. The structures of all compounds were characterized by elemental analysis, IR, MS, and ¹H NMR spectra. The crystal structure of compound 4i was determined by single‐crystal X‐ray diffraction analysis.     

Synthesis and reactions of 3‐amino‐2‐methyl‐3H‐[1,2,4]triazolo[5,1‐b]‐quinazolin‐9‐one and 2‐hydrazino‐3‐phenylamino‐3H‐quinazolin‐4‐one

The reaction of 3‐N‐(2‐mercapto‐4‐oxo‐4H‐quinazolin‐3‐yl)acetamide ( 1 ) with hydrazine hydrate yielded 3‐amino‐2‐methyl‐3H‐[1,2,4]triazolo[5,1‐b]quinazolin‐9‐one ( 2 ). The reaction of 2 with o‐chlorobenzaldehyde and 2‐hydroxy‐naphthaldehyde gave the corresponding 3‐arylidene amino derivatives 3 and 4 , respectively. Condensation of 2 with 1‐nitroso‐2‐naphthol afforded the corresponding 3‐(2‐hydroxy‐naphthalen‐1‐yl‐diazenyl)‐2‐methyl‐3H‐[1,2,4]triazolo[5,1‐b]quinazolin‐9‐one ( 5 ), which on subsequent reduction by SnCl₂ and HCl gave the hydrazino derivative 6. Reaction of 2 with phenyl isothiocyanate in refluxing ethanol yielded thiourea derivative 7. Ring closure of 7 subsequently cyclized on refluxing with phencyl bromide, oxalyl dichloride and chloroacetic acid afforded the corresponding thiazolidine derivatives 8, 9 and 10 , respectively. Reaction of 2‐mercapto‐3‐phenylamino‐3H‐quinazolin‐4‐one ( 11 ) with hydrazine hydrate afforded 2‐hydrazino‐3‐phenylamino‐3H‐quinazolin‐4‐one ( 12 ). The reactivity 12 towards carbon disulphide, acetyl acetone and ethyl acetoacetate gave 13, 14 and 15 , respectively. Condensation of 12 with isatin afforded 2‐[N‐(2‐oxo‐1,2‐dihydroindol‐3‐ylidene)hydrazino]‐3‐phenylamino‐3H‐quinazolin‐4‐one ( 16 ). 2‐(4‐Oxo‐3‐phenylamino‐3,4‐dihydroquinazolin‐2‐ylamino)isoindole‐1,3‐dione ( 17 ) was synthesized by the reaction of 12 with phthalic anhydride. All isolated products were confirmed by their ir, ¹H nmr, ¹³C nmr and mass spectra.     

Dodecahydro‐nido‐undecaborate [B11H12]3–

The deprotonation of the nido‐anion [B₁₁H₁₄]^– by two equivalents of LitBu yields the anion [B₁₁H₁₂]^3–. Three observed ¹¹B NMR shifts of this anion in the ratio 1 : 5 : 5 are in agreement with shifts calculated by the GIAO method on the basis of the ab initio computed geometry. The deprotonation can be reversed, giving back [B₁₁H₁₄]^– via [B₁₁H₁₃]^2–. The thermolysis of [Li(thp)_x]₃[B₁₁H₁₂] in thp at 80 °C leads to the closo‐borate [Li(thp)₃]₂[B₁₁H₁₁] under elimination of LiH. Anhydrous air transforms [B₁₁H₁₂]^3– into the known oxa‐nido‐dodecaborate [OB₁₁H₁₂]^–. The rhoda‐closo‐dodecaborate [L₂RhB₁₁H₁₁]^3– is formed from [B₁₁H₁₂]^3– and RhL₃Cl (L = PPh₃).     

Structural Transformation of Methoxy‐Substituted Benzo[de]benzo[4,5]imidazo[2,1‐a]isoquinolin‐7‐ones

Structural transformation of two methoxy derivatives of benzo[de]benzo[4,5]imidazo[2,1‐a]‐isoquinolin‐7‐one were determined via spectroscopic analysis. The transformation mechanism was proposed as the breakage and reformation of the lactam bond.     

Synthesis and reactions of 11H‐benzo[b]pyrano[3,2‐f]indolizines an pyrrolo[3,2,1‐ij]pyrano[3,2‐c]quinolines

2‐Methyl‐3H‐indoles 1 cyclize with two equivalents of ethyl malonate 2 to form 4‐hydroxy‐11H‐benzo[b]pyrano[3,2‐f]indolizin‐2,5‐diones 3, whereas 2‐mefhyl‐2,3‐dihydro‐1H‐indoles 9 give under similar conditions regioisomer 8‐hydroxy‐5‐methyl‐4,5‐dihydro‐pyrrolo[3,2,1‐ij]pyrano[3,2‐c]quinolin‐7,10‐diones 10 . The pyrone rings of 3 and 9 can be cleaved either by alkaline hydrolysis to give 7‐acetyl‐8‐hydroxy‐10H‐pyrido[1,2‐a]indol‐6‐ones 4 or 5‐acetyl‐6‐hydroxy‐2‐methyl‐1,2‐dihydro‐4H‐pyrrolo‐[3,2,1‐ij]quinolin‐4‐ones 11 , respectively. Chlorination of 3 and 9 with sulfurylchloride gives under subsequent ring opening 7‐dichloroacetyl‐8‐hydroxy‐10H‐pyrido[1,2‐a]indol‐6‐ones 5 or 5‐dichloracetyl‐6‐hydroxy‐2‐methyl‐1,2‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinolin‐4‐ones 12 . The dichloroacetyl group of 5 can be reduced with zinc to 7‐acetyl‐8‐hydroxy‐10H‐pyrido[1,2‐a]indol‐6‐ones 7. Treatment of the acetyl compounds 4, 7 and 11 with 90% sulfuric acid cleaves the acetyl group and yields 8‐hydroxy‐10H‐pyrido[1,2‐a]‐indol‐6‐ones 6 and 8 , and 6‐hydroxy‐2‐methyl‐1,2‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinolin‐4‐ones 13 . Reaction of dichloroacetyl compounds 12 with sodium azide yields 6‐hydroxy‐2‐methyl‐5‐(1H‐tetrazol‐5‐ylcarbonyl)‐1,2‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinolin‐4‐ones 14 via intermediate geminal diazides.     

Pyrrolo[3,4‐e][1,2,3]triazolo[1,5‐a]pyrimidine and pyrrolo[3,4‐d] [1,2,3]triazolo[1,5‐a]pyrimidine. New tricyclic ring systems of biological interest

Derivatives of the new ring system pyrrolo[3,4‐e][1,2,3] triazolo[1,5‐a]pyrimidine 6 were prepared in high yields in one step by reaction of 3‐azidopyrrole 3 and substituted acetonitriles. Compound 6b rearranged, upon heating in dimethyl sulfoxide in the presence of water, to pyrrolo[3,4‐d][1,2,3]triazolo‐[1,5‐a]pyrimidine 7.     

Rearrangement of spiro[2H‐1‐benzopyran‐2,2′‐[2H]indoles] to pyrrolo[1,2‐a]indole derivatives

Heating of 1′‐(N‐substituted carbamoyl)methylspiro[2H‐1‐benzopyran‐2,2′‐[2H]indoles] with potassium hydroxide in ethanol yields diastereomeric 5a,13‐methano‐6H‐1,3‐benzoxazepino[3,2‐a]indole‐12‐carbox‐amides. Reduction of the latter with sodium borohydride affords 1,2,3,9a‐tetrahydro‐2‐hydroxyaryl‐9H‐pyrrolo[ 1,2‐a] indole‐3 ‐carboxamides.     

An Efficient Synthesis of Chromeno[4,3‐d]isoxazolo[5,4‐b]pyridin‐6‐one Derivatives

A series of chromeno[4,3‐d]isoxazolo[5,4‐b]pyridin‐6‐one derivatives were easily and efficiently synthesized by the reaction of 3‐acyl‐2H‐chromen‐2‐ones with isoxazol‐5‐amine in acetic acid. Some synthesized compounds were evaluated for their antiproliferative properties in vitro against cancer cells, and these compounds were found to have some activities.