Spirodienone route for the stereoselective methylene functionalization of p-tert-butylcalix[4]arene.

A new method for the regio- and stereoselective functionalization of two distal methylene groups of p-tert-butylcalixarene (1a) is described. Reaction of the meso bis(spirodienone) calixarene derivative 2a with bromine afforded the tetrabrominated product 3a derived from exo 1,4-additions of bromine to the diene subunits. A phase-transfer-catalyzed reaction of 3a with aqueous NaOH/CH2Cl2 yielded the exo bis(epoxide) calixarene derivative 4. Heating 3a in a vacuum eliminated two molecules of HBr and afforded a product (5b) that retained the C(i) symmetry of the starting material. X-ray analysis indicated that the calixarene derivative 5b possesses two exocyclic double bonds of E configuration. Calixarene 5b undergoes reaction with nucleophiles at the exocyclic double bonds, with concomitant bond shifts and expulsion of the bromine atoms. Selective trans monodeuteration of two methylene groups of 1 was achieved by reaction of 5b with NaBD4 followed by aromatization of the labeled spirodienol derivative. Reaction of 5b with RONa/ROH (R = Me, Et) afforded the methylene-substituted bis(spirodienone) derivatives 9a and 9b possessing two trans alkoxy groups. X-ray crystallography of 9b indicated that the two trans substituents are located at pseudoequatorial positions of the methylene groups. LiAlH4 reduction of the substituted bis(spirodienone) derivatives afforded calix[4]arenes incorporating trans alkoxy groups at two distal methylene positions.     

Reaction of diazoindenothiophenes with mono- and dibenzoylacetylenes

Reaction of diazoindenothiophenes ( 1 and 2 ) with benzoyl acetylene ( 4 ) afforded the rearrangement products ( 6a and b ) of the initial adducts. The major product of the reaction of diazo indenothiophene ( 3 ) with 4 was butadiene derivative 8a . Reaction of 1 with dibenzoylacetylene ( 5a ) gave the rearranged pyrazole ( 12 ), while the reaction of 2 and 3 , afforded the butadiene derivatives ( 8b-d ).     

Functionalization of the methylene bridges of the calix[6]arene scaffold

The bromine atoms of the hexabromo calixarene derivative 3 were replaced by other groups under S(N)1 conditions, allowing the facile synthesis of calix[6]arene derivatives incorporating identical functionalities at all bridges. Heating at reflux a mixture of 3 and the appropriate alcohol incorporated primary and secondary alkoxy substituents. Hydride abstraction was observed when the reaction with EtOH and i-PrOH was conducted in hexafluoroisopropanol (HFIP). Solvolysis of 3 in TFE in the presence of strong nucleophiles (such as N3(-) and aniline) afforded the corresponding hexaazido and hexaanilino derivatives. Hydroxyl groups were incorporated into the calix[6]arene scaffold via acetolysis of 3, followed by LiAlH4 reduction of the hexaacetate derivative obtained. Friedel-Crafts alkylations in the absence of Lewis acids were conducted by heating at reflux a mixture of 3, HFIP, and a substituted benzene derivative (e.g, m-xylene, p-methyl anisole, mesitylene). The calix[6]arene bridges were alkylated by heating at reflux a mixture of 3 and 2,4-pentanedione in TFE or HFIP. In all cases the reaction proceeded with high diastereoselectivity, and the major isomer isolated was assigned to the rc5 (i.e., all-cis) form. NMR spectroscopy indicates that the conformation adopted by the macrocycle possesses 3-fold symmetry (a "pinched cone") that is rigid in the laboratory time scale in the mesityl-substituted derivative.     

Intramolecular AR--O--AR bond formation in calixarenes

The formal dehydration of two vicinal phenol moieties of p-tert-butylcalix[6]arene was achieved in two steps by mild oxidation of the calixarene followed by treatment of the resulting monospirodienone derivative (9c) with an ionic hydrogenation mixture (Et(3)SiH/CF(3)COOH). Reaction of 9c yielded the unsubstituted xanthenocalix[6]arene 11d, while treatment of the monospirodienone derivative of a spherand-type calixarene (13) with Et(3)SiH/CF(3)COOH afforded the dibenzofuran derivative 15. The formation of the latter product indicates that, at least for 13, the rings forming the Ar--O--Ar bond in the product are not those connected by the spiro bond in the starting material. Methylation of the phenolic hydroxyl groups of 11d with methyl p-toluenesulfonate/K(2)CO(3) or dimethyl sulfate/base afforded its dimethyl and tetramethyl ether derivatives. The parent xanthone calix[6]arene derivative 17b was prepared by O-methylation of the phenol groups followed by CrO(3) oxidation of the xanthene methylene group and deprotection of the OH groups. McMurry coupling of calixanthone 17a afforded the dixanthylene 18. Calixarenes 11d and 15 (which possess a xanthene and dibenzofuran group, respectively) were structurally characterized by X-ray crystallography.     

Synthesis of Some Novel 2‐Anilinothiophene, 2,3′‐Bithienyl and Thienylthiopyridine Derivatives Resistance to Penicillium Digitatum Effect the Fruit

Reaction of benzotriazol‐1‐yl acetone 1 with phenyl isothiocyanate followed with α‐chloroacetone or ethyl‐α‐chloroacetate afforded 2‐anilinothiophenes 3 or 4 , respectively. Treatment of 3 with malononitrile at different reaction conditions afforded 6 or 7 . Reaction of 1 with CS₂ in DMF and phenacylbromide afforded S‐alkylated thiophene 10 . Reactions of the latter compound with different active methylene nitriles afforded thienylthiopyridine derivatives 14 and 15 . Condensation of 10 with hydrazine hydrate afforded hydrazon derivative 16 . Reaction of thiophene 17 with formamide in DMF afforded 19 which converted to N‐thienylpyrimidine 20 when treated with malononitrile. The structure of the newly synthesized compounds has been established on the basis of their analytical and spectral data. The compounds were also investigated for antibacterial and antifungal activities.     

Pyrimidines-19: Ring transformation of 5-nitrouracil into nitroresorcinols

The first intermolecular right transformation of a uracil derivative into the benzene system is reported. Treatment of 1,3-dimethyl-5-nitrouracil (1) with acetone in NaOMe/MeOH afforded 6-acetonyl-5,6-dihydro-1,3-dimethyl-5-nitrouracil (6) which was converted into 4-nitroresorcinol (5) upon treatment with NaOEt/EtOH at reflux. Reaction of1 with butanone gave two major products, 3-(5,6-dihydro-1,3-dimethyl-5-nitrouracil-6-yl)butanone (7) and the 1-(uracil-6-yl)butanone isomer (8). Prolonged treatment of7 with NaOEt/EtOH afforded 4-methyl-6-nitro-resorcinol (9) whereas8 was converted into 2-methyl-4-nitro-resorcinol (10). Treatment of1 with diethyl acetonedicar?ylate in NaOEt/EtOH afforded diethyl-2-(5,6-dihydro-1,3-dimethyl-5-nitrouracil-6-yl)-acetonedicar?ylate (2). Prolonged treatment of2 with NaOEt/EtOH at reflux afforded (5,6-dihydro-1,3-dimethyl-6-nitrouracil-6-yl)-acetate (3). Apparently,2 underwent a retroClaisen reaction to give3. Reaction of1 with ethyl acetoacetate in NaOEt/EtOH gave adduct isomers4 which underwent transformation reaction to give eventually 6-nitroresorcinol (5).     

Reaction of arylsulfonylhydrazones of aldehydes with alpha-magnesio sulfones. A novel olefin synthesis

Reactions of representative tosylhydrazones of aldehydes and ketones with alpha-metalated sulfones were examined in order to develop a practical olefination method. Treatment of aldehyde tosylhydrazone 2 with an excess of alpha-lithiated methyl phenyl or dimethyl sulfones yielded 3a. The reaction of 2 with sterically unhindered lithiated alkyl sulfones gave mixtures of the respective olefination products 3b-d along with the Shapiro fragmentation product 4. Sterically hindered lithiated sulfones afforded Shapiro products exclusively. In contrast, aldehyde tosylhydrazones 2 or 6 in reactions with a variety of alpha-magnesio primary or secondary alkyl sulfones gave olefination products 3a-j and 7a-c in high yields (Tables 1 and 2). beta-Branched alkyl sulfones afforded predominantly (E)-alkenes, whereas unhindered primary sulfones gave mixtures of (E)- and (Z)-alkenes with low selectivity. Reaction of the 2,4,6-triisopropylbenzenesulfonylhydrazone (trisylhydrazone) of cyclodecanone 11c with alpha-magnesio methyl phenyl sulfone afforded the methylidene derivative 12a contaminated with the Shapiro product 13. Tosylhydrazone 2 resisted reaction with i-PrMgCl and gave only a small amount of the addition product in reaction with Bu(2)Mg. Some mechanistic aspects of the reaction of tosylhydrazones with organomagnesium compounds are discussed.     

Synthesis of novel acyclonucleosides. Reactions of 1-(2-oxopropyl)pyridazin-6-ones

Multi-substituted-1-(1-bromo-2-oxopropyl)pyridazin-6-ones 3, 4 , multi-substituted-1-(1,1-dibromo-2-oxopropyl)pyridazin-6-ones 7, 8 , and multi-substituted-1-(3-bromo-2-oxopropyl)pyridazin-6-ones 5, 6 were synthesized from the corresponding 1-(2-oxopropyl)pyridazin-6-ones 1, 2 by the selective bromination in acidic or neutral medium. And treatment of 1,1-dibromo-2-oxopropyl derivatives 7, 8 with aqueous potassium carbonate gave the corresponding pyridazin-6-ones 9, 10 by the dealkylation. Reaction of 1 with methanolic potassium cyanide afforded only the corresponding 4-methoxy derivative 11 , whereas reaction of 2 with methanolic potassium cyanide gave 4-methoxy derivative 12 and 2-cyano-2-hydroxypropyl derivative 13 . Reaction of 1 and 2 with hydroxylamine in methanol afforded the corresponding syn-2-hydroxyiminopropyl derivatives 14 and 15 .     

Ring-opening reactions of 3-substituted 1-azabicyclo[1.1.0]butane with dichlorocarbene

Reaction of 3-ethyl-1-azabicyclo[1.1.0]butane ( 1a ) with chloroform-potassium tert-butoxide afforded a ring-opened product, 1,1-dichloro-2-aza-4-ethylpenta-1,4-diene ( 4a ), which was characterized via conversion to the corresponding N-substituted 5-chloro-1,2,3,4-tetrazole, Sa . Reaction of 3-phenyl-1-azabicyclo-[1.1.0]butane ( 1b ) with “Seyferth's reagent” (PhHgCCl₂Br) afforded 1,1-dichloro-2-aza-4-phenylpenta-1,4-diene ( 4b ), which also was characterized via conversion to a tetrazole derivative, i.e., 5b . Finally, the reaction of 1b with dichlorocarbene generated under phase transfer conditions (chloroform-sodium hydroxide-TEBA) was studied. At short reaction times (0.5 hour), the major reaction product was 4b . However, at longer reaction times (20–30 hours), two secondary products, 8 and 9 , were formed which resulted via subsequent dichlorocyclopropanation of 4b .     

Syntheses, structures and luminescent properties of new lanthanide-based coordination polymers based on 1,4-benzenedicarboxylate (bdc)

Reaction of 1,4-benzenedicarboxylic acid (1,4-H(2)BDC) with EuCl(3).6H(2)O in MeOH in the presence of Et(3)N and MeCN gives a mixture of the 3-D metal-organic-framework (MOF) materials [Eu(2)(1,4-BDC)(3)(MeOH)(4)].8MeOH () and 2-D [Eu(1,4-BDC)(MeOH)(4)].Cl.MeOH.0.25H(2)O (). Similar reactions afforded the isomorphous Gd () and Tb () analogs of . Reaction of 1,4-H(2)BDC with Ln(NO(3))(3).6H(2)O under similar conditions gave [Ln(BDC)NO(3)(MeOH)(2)].MeCN.H(2)O (Ln = Eu () and Gd ()), which have 2-D framework structures. The structures of were determined by single crystal X-ray crystallographic studies and the luminescence properties of and in DMF solution were determined.     

Bis(nitro- and polynitromethyl-ONN-azoxy)azoxyfurazans and some of their derivatives

Reaction of diamino derivative of azoxyfurazan with 2,2-dimethyl-5-nitro-5-nitroso-1,3-dioxane in the presence of dibromoisocyanuric acid afforded bis(2,2-dimethyl-5-nitro-1,3-dioxan-5-yl-ONN-azoxy)azoxyfurazan. The reaction of the latter with AcCl/MeOH and further transformations of the product gave the first representative of substituted (mono- and polynitroalkyl-ONN-azoxy)azoxyfurazans, e.g. bis(nitromethyl-ONN-azoxy)azoxyfurazan, bis(dinitromethyl-ONN-azoxy)azoxyfurazan, bis(trinitromethyl-ONN-azoxy)azoxyfurazan, and some of their derivatives.     

Syntheses of substituted 1-methyl-2-(1,3,4-thiadiazol-2-yl)-4-nitropyrroles and 1-methyl-2-(1,3,4-oxadiazol-2-yl)-4-nitropyrroles

Starting from readily available ethyl-4-nitropyrrole-2-carboxylate ( 1 ), substituted 1-methyl-2-(1,3,4-thiadiazol-2-yl)-4-nitropyrroles and 1-methyl-2-(1,3,4-oxadiazol-2-yl)-4-nitropyrroles were prepared. The reaction of 1 with diazomethane gave ethyl 1-methyl-4-nitropyrrole-2-carboxylate ( 2 ). Reaction of compound 2 with hydrazine hydrate afforded the corresponding hydrazide 3 . The reaction of 3 with formic acid yielded 1-(1-methyl-4-nitropyrrole-2-carboxyl)-2-(formyl)hydrazine ( 7 ). Refluxing of the latter with phosphorus pentasulfide in xylene yielded compound 6 in 40% yield. Reaction of compound 7 with phosphorus pentoxide afforded compound 9 . Reaction of compound 3 with 1,1′-carboxyldiimidazole in the presence of triethylamine yielded 2-(1-methyl-4-nitro-2-pyrrolyl)-1,3,4-oxadiazoline-4(H)-5-one ( 11 ). Refluxing compound 3 with cyanogen bromide in methanol gave compound 12 . Compound 13 could be obtained through the reaction of compound 3 with carbon disulfide in basic medium. Alkylation of compound 13 afforded the correspanding alkylthio derivative 14 . Reaction of 1-methyl-4-nitropyrrole-2-carboxylic acid ( 15 ) with thiosemicarbazide and phosphorus oxychloride gave 2-amino-5-(1-methyl-4-nitro-2-pyrrolyl)-1,3,4-thiadiazole ( 16 ). Sandmeyer reaction of compound 16 yielded 2-chloro-5-(1-methyl-4-nitro-2-pyrrolyl)-1,3,4-thiadiazole ( 17 ). Refluxing of the latter with thiourea afforded 2-(1-methyl-4-nitro-2-pyrrolyl)-1,3,4-thiadiazoline-4(H)-5-thione ( 18 ). Alkylation of compound 18 gave the corresponding alkylthio derivative 19 . Oxidation of the latter with hydrogen peroxide in acetic acid yielded 2-(1-methyl-4-nitro-2-pyrrolyl)-5-methylsulfonyl-1,3,4-thiadiazole ( 20 ).     

Furopyridines. VI. Preparation and reactions of 2- and 3-substituted furo[2,3-b]pyridines

This paper describes the synthesis and chemical properties of some 2- and 3-substituted furo[2,3-b]pyridines. Reaction of ethyl 2-chloronicotinate 1 with sodium ethoxycarbonylmethoxide or 1-ethoxycarbonyl-1-ethoxide gave β-keto ester 2 or ketone 5 , respectively. Ketonic hydrolysis of 2 afforded ketone 3, from which furo[2,3-b]pyridine 4 was obtained by the method of Sliwa. While, 2-methyl derivative 7 was prepared from 5 by reduction, O-acetylation and the subsequent pyrolysis. Reaction of ketone 3 with methyllithium gave tertiary alcohol 8 which was O-acetylated and pyrolyzed to give 3-methyl derivative 9 . Formylation of 4 , via lithio intermediate, with DMF yielded 2-formyl derivative 10 , from which 7 , was obtained by Wolff-Kishner reduction. Dehydration of the oxime 11 of 10 gave 2-cyano derivative 12 , which was hydrolyzed to give 2-carboxylic acid 13 . Reaction of 3-bromo compound 14 with copper(I) cyanide gave 3-cyano derivative 15 . Alkaline hydrolysis of 15 afforded compound 16 and 17 , while acidic hydrolysis gave carboxamide 18 . Reduction of 15 with DIBAL-H afforded 3-formyl derivative 19 . Wolff-Kishner reduction of 19 gave no reduction product 9 but hydrazone 20 . Reduction of tosylhydrazone 21 with sodium borohydride in methanol afforded 3-methoxymethylfuro[2,3-b]pyridine 22 .     

Trisannelation of acrylates to 1,3,5-benzenetricarboxylates by a Pd(OAc)2/HPMoV/CeCl3/O2 system

A new type of trisannelation reaction of acrylates through acetal formation was developed by Pd(OAc)2 combined with molybdovanadophosphoric acid (HPMo8V4) and Lewis acid under atmospheric dioxygen. Thus, the reaction of isobutyl acrylate in the presence of Pd(OAc)2, HPMo8V4, and CeCl3 under O2 (1 atm) in MeOH/AcOH afforded isobutyl 1,3,5-benzenetricarboxylate in fair yield. The reaction was found to proceed through the palladium-catalyzed acetalization of acrylate with methanol followed by the trisannelation reaction of the resulting acetal promoted by CeCl3.     

Synthesis and Some Reactions of Quinoxalinecarboazides

Chlorination of ethyl(quinoxalin‐2(1H)one)‐3‐carboxylate 1 gave ethyl (2‐chloroquinoxaline)‐3‐carboxylate 2 ;thionation of 1 by P₂S₅ or 2 by thiourea yielded the same product 3 . Reaction of chloro compound 2 or thiocompound 3 with hydrazine hydrate gave pyrazolylquinoxaline 4 . The reaction of ester 1 with thiourea or hydrazine hydrate afforded pyrimido quinoxaline 5 or carbohydrazide 6 ; the reaction of 6 with carbon disulfide in basic medium followed by alkylation afforded oxadiazoloquinoxaline derivatives 7, 8a,b . Carboazide 9 was produced by reaction of 5 with nitrous acid. Compound 9 on heating in an inert solvent, with or without amines, in alcohols or hydrolysis in H₂O undergoes Curtius rearrangments to yield 10‐13 . Reaction of 13 with thiosemicarbazide gave triazoloquinoxaline 14 which on reaction with alkylhalides or hydrazine hydrate yielded 15a‐c while hydrolysis of 13 gave 3‐aminoquinoxalinone 16 which was used as an intermediate to produce 17‐20 .     

Self-assembly of a cyclic metalladecapyridine from the reaction of 2,6-bis(bis(2-pyridyl)methoxymethane)pyridine with silver(I)

Reaction of Ag( p-MeC 6H 4SO 3) with 2,6-bis(bis(2-pyridyl)methoxymethane)pyridine (PY5) in CH 2Cl 2 gave [Ag (I) 2(PY5) 2](p-MeC 6H 4SO 3) 2 (1). Treatment of 2,6-bis(bis(2-pyridyl)hydroxymethane)pyridine (PY5-OH) with AgNO 3 in MeOH gave [Ag (I) 2(PY5-OH) 2](NO3) 2 (2); in the presence of PPh 3, this reaction afforded [Ag (I)(PY5-OH)(PPh 3)]NO 3 (3). The structures of 1- 3 have been determined by X-ray crystal analysis, revealing four-coordinate Ag (I) ions in these complexes. Both 1 and 2 feature a quadruply branched 28-membered C 16N 10M 2 metallamacrocycle fused to 10 pyridyl groups. On the basis of (1)H NMR measurements, the dinuclear 1 and 2 dissociate into a mononuclear complex upon dissolving in MeCN but in MeOH an equilibrium between the mono- and dinuclear species can be detected.     

Pyridazine Derivatives and Related Compounds,Part 17: 1 The Synthesis of Some 3-Substituted Pyridazino[3′, 4′:3, 4]pyrazolo[5, 1-c]-1,2,4-triazines and Their Antimicrobial Activity

The reaction of the hydrazide of pyridazino[3′, 4′:3, 4]pyrazolo[5, 1-c]-1,2,4-triazine-3-carboxylic acid 3 with carbon disulfide in the presence of potassium hydroxide gave the 1,3,4-oxadiazole-2-thione derivative 4. The methylation of this product in an alkaline medium proceeds at the sulfur atom. The reaction of 3 with KOH and carbon disulfide followed by addition of hydrazine hydrate afforded the 4-amino-1,2,4-triazole derivative 6. Compound 3, when heated either with ammonium thiocyanate or with potassium thiocyanate, afforded the same product 7, which underwent cyclodehydration in the presence of acetyl chloride, which led to the 2-acetylamino-1,3,4-thiadiazole derivative 8. In a basic medium, the product was 1,2,4-triazole-3-thione derivative 9. The reaction of 3 with phenyl isothiocyanate provided thiosemicarbazide derivative 10, which underwent cyclodehydration in a basic medium and gave the 1,2,4-triazole derivative 11. The reaction of 3 with formic acid yielded the 3-carboxyl-2′-(formyl)hydrazine derivative 12. The refluxing of the latter with phosphorus pentasulfide in xylene yielded compound 14 (65%). The reaction of compound 12 with phosphorus pentoxide afforded compound 15. Some representative examples were screened for antimicrobial activity.     

Synthesis of (R)-(+)-tanikolide through stereospecific C-H insertion reaction of dichlorocarbene with optically active secondary alcohol derivatives

Stereospecific alpha C-H insertion reaction of protected chiral 1,2-glycols, (S)-1,2-isopropylidenedioxytridecane (3) and ethyl (S)-4,5-isopropylidenedioxy-pentanoate (4), prepared from (R)-glyceraldehyde acetonide (2), with dichlorocarbene generated from CHCl(3)/50% NaOH/cetyltrimethylammonium chloride (as ptc.) took place with complete retention of configuration to provide (S)-4-dichloromethyl-2,2-dimethyl-4-undecyl-1,3-dioxolane (5) and ethyl (S)-3-(4-dichloromethyl-2,2-dimethyl-1,3-dioxolan-4-yl)-propanoate (8), respectively. The ester (8) was transformed to 5 by elongation of the side chain. The glycol derivative (5) was converted into O-TBDPS-protected (S)-2-hydroxymethyl-2-undecyloxirane (16). Reaction of 16 with a cuprate reagent containing homoallylic carbon chain followed by oxidative manipulation of the terminal olefin afforded (R)-(+)-tanikolide (1).     

Synthesis of the sialyl Lewis X epitope attached to glycolipids with different core structures and their selectin-binding characteristics in a dynamic test system

Sialyl Lewis X (sLeX)/selectin-mediated leukocyte rolling along endothelial cells has recently gained wide interest. In this paper the influence of the spacer length of laterally clustered neoglycolipids 1a-d on cell rolling in a dynamic test system is investigated. The required di-O-hexadecyl glycerols with none, and with three, six, or nine ethylene glycol units as spacer groups (compounds 4a-d) could be readily obtained. The synthesis of 1-O-thexyldimethylsilyl-protected sLeX 24 was based on sialylation of 2,3,4-O-unprotected galactose derivative 11 with sialyl phosphite 8 as donor; this afforded the desired disaccharide 12, which was transformed into trichloroacetimidate 14 as disaccharide donor. Reaction of 3-O-unprotected glucosamine derivative 18 with fucosyl donor 20 afforded disaccharide 21, which was transformed into the 4-O-unprotected derivative 23. Reaction of 14 with 23 furnished the desired tetrasaccharide 24 in good yield. Transformation of 24 into the trichloroacetimidate 26 as donor, followed by the reaction with 4a-d as acceptor gave, after deprotection, the target molecules 1a-d. For comparison, 4d was also connected with a sialyl residue (-->31) and with an N-acetylglucosamine residue (-->34). Compounds 1c and 1d with a hexaethylene glycol and a nonaethylene glycol spacer, respectively, were much more efficient in mediating selectin-dependent cell rolling in the dynamic test system than compounds 1a and 1b, which had no spacer (1a), or only a triethylene glycol spacer (1b).     

Preparation of diynes via selective bisalkynylation of zirconacycles

Reaction of alkynyl halides with in situ prepared zirconacyclopentanes, -pentenes, and -pentadienes in the presence of CuCl under mild reaction conditions afforded alkynes or diynes. Control of the reaction conditions selectively afforded monoalkynylation products of zirconacycles. Reaction of zirconacycles with 2 equiv of alkynyl halides resulted in the formation of diynes. Selective monoalkynylation of zirconacycle with an alkynyl halide, followed by reaction with a different alkynyl halide, afforded unsymmetrical diynes. Bisalkynylation product of zirconacyclopentadiene was gradually converted into a tricyclic compound.