Synthese und Struktur hochfunktionalisierter 2, 3‐Dihydro‐1H‐1, 3, 2‐diazaborole

Synthesis and Structure of Highly Functionalized 2, 3‐Dihydro‐1H‐1, 3, 2‐diazaboroles A series of differently substituted 2, 3‐dihydro‐1H‐1, 3, 2‐diazaboroles has been prepared by various methods. 1, 3‐Di‐tert‐butyl‐2‐trimethylsilylmethyl‐1H‐1, 3, 2‐diazaborole ( 7 ), 2‐isobutyl‐1, 3‐bis(1‐cyclohexylethyl)‐1H‐1, 3, 2‐diazaborole ( 8 ), 1, 3‐bis‐(1‐cyclohexylethyl)‐2‐trimethylsilylmethyl‐1H‐1, 3, 2‐diazaborole ( 9 ) 1, 3‐bis(1‐methyl‐1‐phenyl‐propyl)‐2‐trimethylsilylmethyl‐1H‐1, 3, 2diazaborole ( 10 ) and 2‐bromo‐1, 3‐bis(1‐methyl‐1‐phenyl‐propyl)‐1H‐1, 3, 2‐diazaborole ( 11 ) were formed by reaction of the corresponding 1, 4‐diazabutadienes with the boranes Me₃SiCH₂BBr₂, iBuBBr₂ and BBr₃ followed by reduction of the resulting borolium salts [R¹ = tBu, Me(cHex)CH, [Me(Et)Ph]C; R² = Me₃SiCH₂, iBu, Br] with sodium amalgam. Treatment of 11 and 12 with silver cyanide afforded the 2‐cyano‐1, 3, 2‐diazaboroles 13 and 14 . An alternative route to compound 8 is based on the alkylation of 2‐bromo‐1, 3, 2‐diazaborole 12 with isobutyllithium. Equimolar amounts of 13 and isobutyllithium give rise to the formation of 15 . The new compounds were characterized by ¹H‐, ¹³C‐, ¹¹B‐NMR, IR and mass spectra. The molecular structures of 7 and meso ‐10 were confirmed by x‐ray structural analysis.     

Synthese und Reaktivität von 2‐Brom‐1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol Molekülstruktur von Bis(1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol‐2‐yl)

Synthesis and Reactivity of 2‐Bromo‐1,3‐diethyl‐2,3‐dihydro‐1 H ‐1,3,2‐benzodiazaborole Molecular Structure of Bis(1,3‐diethyl‐2,3‐dihydro‐1 H ‐1,3,2‐benzodiazaborol‐2‐yl The reaction of a slurry of calcium hydride in toluene with N,N′‐diethyl‐o‐phenylenediamine ( 1 ) and boron tribromide affords 2‐bromo‐1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol ( 2 ) as a colorless oil. Compound 2 is converted into 2‐cyano‐1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborole ( 3 ) by treatment with silver cyanide in acetonitrile. Reaction of 2 with an equimolar amount of methyllithium affords 1,3‐diethyl‐2‐methyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborole ( 4 ). 1,3,2‐Benzodiazaborole is smoothly reduced by a potassium‐sodium alloy to yield bis(1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol‐2‐yl] ( 7 ), which crystallizes from n‐pentane as colorless needles. Compound 7 is also obtained from the reaction of 2 and LiSnMe₃ instead of the expected 2‐trimethylstannyl‐1,3,2‐benzodiazaborole. N,N′‐Bis(1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol‐2‐ yl)‐1,2‐diamino‐ethane ( 6 ) results from the reaction of 2 with Li(en)C≡CH as the only boron containing product. Compounds 2 – 4 , 6 and 7 are characterized by means of elemental analyses and spectroscopy (IR, ¹H‐, ¹¹B{¹H}‐, ¹³C{¹H}‐NMR, MS). The molecular structure of 7 was elucidated by X‐ray diffraction analysis.     

Syntheses,Structure, Electrochemistry,and Optical Properties of 1,3‐Diethyl‐2,3‐dihydro‐1‐H‐1,3,2‐pyrido‐[4,5‐b]‐diazaboroles

Reaction of 2,5‐bis(dibromoboryl)thiophene ( 4 ) or 1,4‐bis(dibromoboryl)benzene ( 6 ) with two equivalents of N,N′‐dilithiated 2,3‐diaminopyridine ( 3 ) led to the generation of the pyridodiazaboroles 5 and 7 in which the two diazaborole rings are linked by 2,5‐thiophen‐diyl or 1,4‐phenylene units via the boron atom. The novel compounds were characterized by elemental analyses and spectroscopy (¹H‐, ¹¹B‐, ¹³C‐NMR, MS, and UV‐VIS). The molecular structure of 5 was elucidated by X‐ray diffraction. Cyclovoltammograms of 5 and 7 show two irreversible oxidation waves at 0.76 and 0.73 V, respectively vs Fc/Fc⁺. The novel compounds display intense blue luminescence with Stokes shifts of 76 and 74 nm and relative quantum yields of 39 and 43 % vs Coumarin 120 (Φ = 50 %).     

Synthese,Struktur, Elektrochemie und optische Eigenschaften von alkinylfunktionalisierten 1,3,2‐Diazaborolen und 1,3,2‐Diazaborolidinen

Syntheses, Structures, Electrochemistry and Optical Properties of Alkyne‐Functionalized 1,3,2‐Diazaboroles and 1,3,2‐Diazaborolidenes The reaction of 2‐bromo‐1,3‐ditert‐butyl‐2,3‐dihydro‐1H‐1,3,2‐diazaborole ( 3 ) with lithiated tert‐butyl‐acetylene and lithiated phenylacetylene affords the 2‐alkynyl‐functionalized 1,3,2‐diazaboroles 4 and 5 as a thermolabile colorless oil ( 4 ) or a solid ( 5 ). Similarly 2‐bromo‐1,3‐diethyl‐2,3‐dihydro‐1H‐1,3,2‐benzodiazaborole ( 6 ) was converted into the crystalline 2‐alkynyl‐benzo‐1,3,2‐diazaboroles 7 and 8 by treatment with LiC≡C–tBu or LiC≡CPh, respectively. 2‐Ethynyl‐1,3‐ditert‐butyl‐2,3‐dihydro‐1H‐1,3,2‐diazaborole ( 2 ) was metalated with tert‐butyl‐lithium and subsequently coupled with 2‐bromo‐1,3,‐ditert‐butyl‐2,3‐dihydro‐1H‐1,3,2‐diazaborole ( 3 ) to afford bis(1,3‐ditert‐butyl‐2,3‐dihydro‐1H‐1,3,2‐diazaborol‐2‐yl)acetylene ( 9 ) as thermolabile colorless crystals. Analogously coupling of the lithiated species with 6 or with 2‐bromo‐1,3‐ditert‐butyl‐1,3,2‐diazaborolidine ( 11 ) gave the unsymmetrically substituted acetylenes 10 or 12 , respectively, as colorless solids. Compounds 4 , 5 , 7 – 10 and 12 are characterized by elemental analyses and spectroscopy (IR, ¹H‐, ¹¹B{¹H}, ¹³C{¹H}‐NMR, MS). The molecular structures of 5 , 8 and 9 were elucidated by X‐ray diffraction analyses.     

Synthesis and Properties of 2,3‐Dihydro‐1H‐corannuleno[2,3‐cd]pyridine (=2,3‐Dihydro‐1H‐dibenzo[1,10 : 6,7]fluorantheno[3,4‐cd]pyridine) Derivatives: Heterocyclic peri‐Anellated Corannulenes

The anellation of a 6‐membered ring to the 2,3‐position of corannulene (=dibenzo[ghi,mno]fluoranthene; 1 ) leads to curved aromatic compounds with a significantly higher bowl‐inversion barrier than corannulene (see Fig. 1). If the bridge is −CH₂−NR−CH₂−, a variety of linkers can be introduced at the N(2) atom, and the corresponding curved aromatics act as versatile building blocks for larger structures (see Scheme). The locked bowl, in combination with an amide bond (see 9 and 10 ), gives rise to corannulene derivatives with chiral ground‐state conformations, which possess the ability to adapt to their chiral environment by shifting their enantiomer equilibrium slightly in favor of one enantiomeric conformer. Rim annulation of corannulene seems to display a significantly lower electron‐withdrawing effect than facial anellation on [5,6]fullerene‐C₆₀‐I_h, as determined by an investigation of the basicity at the N‐atom of CH₂−NR−CH₂ (see 4 vs. 15 in Fig. 2).     

The Photocyclodimers of 2,3‐Dihydro‐2,2‐dimethyl‐4H‐pyran‐4‐one

On irradiation (350 nm) in benzene solution, dihydropyranone 3 affords predominantly (75%) the cis‐anti‐cis HH‐dimer 4 , but in smaller amounts (12%) also dimer 5 , wherein one of the six‐membered rings is trans‐fused to the (central) cyclobutane ring. The constitution and configuration of 5 was fully elucidated by NMR‐analysis. On contact with SiO₂, 5 isomerizes quantitatively to the cis‐anti‐cis HT‐dimer 7 , the structure of which was established by X‐ray crystal‐structure determination.     

Copper(II) Halide Complexes with 1‐tert‐Butyl‐1H‐1,2,4‐triazole and 1‐tert‐Butyl‐1H‐tetrazole

1‐tert‐Butyl‐1H‐1,2,4‐triazole (tbtr) was found to react with copper(II) chloride or bromide to give the complexes [Cu(tbtr)₂X₂]_n and [Cu(tbtr)₄X₂] (X = Cl, Br). 1‐tert‐Butyl‐1H‐tetrazole (tbtt) reacts with copper(II) bromide resulting in the formation of the complex [Cu₃(tbtt)₆Br₆]. The obtained crystalline complexes as well as free ligand tbtr were characterized by elemental analysis, IR spectroscopy, thermal and X‐ray analyses. For free ligand tbtr, ¹H NMR and ¹³C NMR spectra were also recorded. In all the complexes, tbtr and tbtt act as monodentate ligands coordinated by Cu^II cations via the heteroring N⁴ atoms. The triazole complexes [Cu(tbtr)₂Cl₂]_n and [Cu(tbtr)₂Br₂]_n are isotypic, being 1D coordination polymers, formed at the expense of single halide bridges between neighboring copper(II) cations. The isotypic complexes [Cu(tbtr)₄Cl₂] and [Cu(tbtr)₄Br₂] reveal mononuclear centrosymmetric structure, with octahedral coordination of Cu^II cations. The tetrazole compound [Cu₃(tbtt)₆Br₆] is a linear trinuclear complex, in which neighboring copper(II) cations are linked by single bromide bridges.     

Über Umlagerungen bei der Cyclialkylierung von Arylpentanolen zu 2,3‐Dihydro‐1H‐inden‐Derivaten, 1. Mitteilung

On Rearrangements by Cyclialkylations of Arylpentanols to 2,3‐Dihydro‐1 H ‐indene Derivatives. Part 1. An Unexpected Rearrangement by the Acid‐Catalyzed Cyclialkylation of 4‐(2‐Chlorophenyl)‐2,4‐dimethyl pentan‐2‐ol under Formation of trans ‐4‐Chloro‐2,3‐dihydro‐1,1,2,3‐tetramethyl‐1 H ‐indene The acid‐catalyzed cyclialkylation of 2,4‐dimethyl‐4‐phenylpentan‐2‐ol led exclusively to the expected product, 2,3‐dihydro‐1,1,3,3‐tetramethyl‐1H‐indene. However, analogous cyclialkylation of 4‐(2‐chlorophenyl)‐2,4‐dimethylpentan‐2‐ol ( 1 ) gave a ca. 1 : 1 mixture of 4‐chloro‐2,3‐dihydro‐1,1,3,3‐tetramethyl‐1H‐indene ( 2 ) and of trans‐4‐chloro‐2,3‐dihydro‐1,1,2,3‐tetramethyl‐1H‐indene ( 3 ; Scheme 1). The specific action of the Cl substituent is investigated and a mechanism for this unexpected frame‐work transposition proposed.     

Synthesis,Characterization and Crystal Structure of Some Novel 1‐Aryl‐2‐Thioxo‐2,3‐Dihydro‐1H‐Quinazolin‐4‐Ones

The base catalyzed intramolecular nucleophilic cyclization of 1‐(2‐haloaroyl)‐3‐aryl thioureas ( 1a‐i ), in the presence of DMF afforded the 1‐aryl‐2‐thioxo‐2,3‐dihydro‐1H‐quinazolin‐4‐ones ( 2a‐i ). The structures were confirmed by spectroscopic data, elemental analyses and in case of the 2c by single crystal X‐ray diffraction data. The mechanistic studies support an intramolecular nucleophilic substitution (S_NAr mechanism) rather than intramolecular aromatic substitution (S_RN1 mechanism).     

A Convenient Synthesis of 2,3‐Dihydro‐3‐methylidene‐1H‐isoindol‐1‐ones by Reaction of 2‐Formylbenzo­nitriles with Dimethyloxosulfonium Methylide

A facile method for the synthesis of 2,3‐dihydro‐3‐methylidene‐1H‐isoindol‐1‐one and its derivatives carrying substituent(s) at C(5) and/or C(6) has been developed. The reaction of 2‐formylbenzonitrile ( 1a ) with dimethyloxosulfonium methylide, generated by the treatment of trimethylsulfoxonium iodide with NaH in DMSO/THF at 0°, resulted in the formation of 2,3‐dihydro‐3‐methylidene‐1H‐isoindol‐1‐one ( 2a ) in 77% yield. Similarly, six 2‐formylbenzonitriles carrying substituent(s) at C(4) and/or C(5), i.e., 1b – 1g , also gave the corresponding expected products 2b – 2g in comparable yields.     

Synthesis of 2‐substituted‐2,3‐dihydro‐5‐benzoyl‐1H‐1,3,2‐benzodiazaphosphole 2‐oxides/sulfides

Syntheses of 2‐aryloxy/2‐chloro ethoxy‐2,3‐dihydro‐5‐benzoyl‐1H‐1,3,2‐benzodiaza‐phosphole 2‐oxides 3a–h were accomplished by reactions of equimolar quantities of 3,4‐diaminobenzophenone ( 1 ) with various aryl/chloroethoxy phosphorodichloridates 2a–g and 2h in the presence of triethylamine at 50–60°C. Compounds 3i–k were prepared by reacting 3,4‐diaminobenzophenone ( 1 ) with aryl thiophosphorodichloridates 2i–k under similar conditions. They were characterized by IR, ¹H, ¹³C, and ³¹P NMR spectral data. Some of these products possessed siginificant antimicrobial activity © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:340–345, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10044     

Synthesis and antimicrobialactivity of 2‐alkylcarbamato‐2,3‐dihydro‐5‐propylthio‐1H‐1,3,2‐benzodiazaphosphole 2‐oxides

Novel 2‐alkylcarbamato/thiocarbama‐to‐2,3‐dihydro‐5‐propylthio‐1H‐1,3,2‐benzodiazaphos‐phole 2‐oxides ( 4a–J ) were synthesized by cyclization of 4‐propylthio‐1,2‐phenylenediamine ( 3 ) with the corresponding dichlorophosphoryl carbamates/thiocarbamates ( 2a–J ) that were obtained by the addition of alcohols/thiols to isocyanatophosphoryl dichloride ( 1 ). The structures of the title compounds were confirmed by the ¹H, ¹³C, ³¹P NMR, and mass spectral studies. Some of these products were found to possess significant antimicrobial activity. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:336–340, 2000     

2,3‐Dihydro‐3,3‐dimethylspiro[1H‐4‐oxanthracene‐5,2′‐oxiran]‐10(5H)‐one

The central six‐membered ring in the title compound, C₁₆H₁₆O₃, is almost planar (and almost coplanar with the aromatic ring), despite one of its C atoms being formally sp³ hybridized. The planarity is a consequence of the C atom at the centre of the spiro­cyclic system also being part of the three‐membered epoxide ring. The mol­ecules are linked by π–­π and C—H?π interactions.     

A Novel and Efficient Synthesis of 3‐[(4,5‐Dihydro‐1H‐pyrrol‐3‐yl)carbonyl]‐2H‐chromen‐2‐ones (=3‐[(4,5‐Dihydro‐1H‐pyrrol‐3‐yl)carbonyl]‐2H‐1‐benzopyran‐2‐ones)

An efficient one‐pot synthesis of 3‐[(4,5‐dihydro‐1H‐pyrrol‐3‐yl)carbonyl]‐2H‐chromen‐2‐one (=3‐[(4,5‐dihydro‐1H‐pyrrol‐3yl)carbonyl]‐2H‐1‐benzopyran‐2‐one) derivatives 4 by a four‐component reaction of a salicylaldehyde 1 , 4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one, a benzylamine 2 , and a diaroylacetylene (=1,4‐diarylbut‐2‐yne‐1,4‐dione) 3 in EtOH is reported. This new protocol has the advantages of high yields (Table), and convenient operation. The structures of these coumarin (=2H‐1‐benzopyran‐2‐one) derivatives, which are important compounds in organic chemistry, were confirmed spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this reaction is proposed (Scheme 2).     

Über Umlagerungen bei der Cyclialkylierung von Arylpentanolen zu 2,3‐Dihydro‐1H‐inden‐Derivaten, 4. Mitteilung

On Rearrangements by Cyclialkylations of Arylpentanols to 2,3‐Dihydro‐1 H ‐indene Derivatives. Part 4. The Acid‐Catalyzed Cyclialkylation of 2,4‐Dimethyl‐2‐phenyl[3‐ ¹³ C]pentan‐3‐ol The cyclialkylation of 2,4‐dimethyl‐2‐phenyl[3‐¹³C]pentan‐3‐ol ( 4 ) gives only 2,3‐dihydro‐1,1,2,3‐tetramethyl‐1H‐[3‐¹³C]indene ( 6 ) (cf. Scheme 2) and not a trace of the isotopomeric 2,3‐dihydro‐1,1,2,3‐tetramethyl‐1H‐[2‐¹³C]indene ( 5 ). The mechanism proposed in [3] for the cyclialkylation of 4 (cf. Scheme 2, Path A) has, therefore, to be abandoned. The mechanism of Scheme 2, Path B, is proposed and may be considered as definitively established.     

Über Umlagerungen bei der Cyclialkylierung von Arylpentanolen zu 2,3‐Dihydro‐1H‐inden‐Derivaten, 5. Mitteilung

On Rearrangements by Cyclialkylations of Arylpentanols to 2,3‐Dihydro‐1 H ‐indene Derivatives. Part 5. The Acid‐Catalyzed Cyclialkylation of 2‐(2‐Chlorophenyl)‐2,4‐dimethylpentan‐3‐ol The mechanism proposed in [1] to explain the surprising result of the cyclialkylation of 4‐(2‐chlorophenyl)‐2,4‐dimethylpentan‐2‐ol ( 3 , R=Me), which gives not only the ‘normal' product, i.e., the 4‐chloro‐2,3‐dihydro‐1,1,3,3‐tetramethyl‐ ( 4 ), but also the isomer trans‐4‐chloro‐2,3‐dihydro‐1,1,2,3‐tetramethyl‐1H‐inden ( 5 ), could be differentiated in two sections (cf. Scheme 2): the first from 3 to the intermediary ion IIa ⇌ IIb , and the second from the latter ions to the final product 5 . For the first section, a sufficiently satisfactory explanation has been given in [1]; the second section has received important support from the mechanisms of the cyclialkylation of 2,4‐dimethyl‐2‐phenylpentan‐3‐ol ( 6 ), the precursor of II′a , the ion IIa without the o‐Cl substituent (cf. Schemes 2, 3 and 5 and [4]). The present communication gives an explanation of the influence of the o‐Cl substituent: a mechanism is proposed for the very complex cyclialkylation of 2‐(2‐chlorophenyl)‐2,4‐dimethylpentan‐3‐ol ( 11 ; cf. Scheme 9). Both mechanism may be considered as definitive. It is very surprising that, by the cyclialkylation of the compounds 1, 3, 8, 11, 15 , and 17 , only compound 1 gives the ‘normal' product; the cyclialkylation of all other phenylpentanols follows complex pathways including Et, i‐Pr, and Ph migrations, which could not be expected. In addition, it has been established that the transformation of 21 to 22 (cf. Scheme 12) and that of 23 to 24 (cf. Scheme 13) occur through two consecutive 1,2‐ and not through a single 1,3‐hydride migration or through an elimination‐addition process (cf. Scheme 13). It can be assumed that the transformation of ion IV (the 2‐(2‐chlorophenyl)‐3,4‐dimethylpent‐2‐ylium ion) to the ion V (the 4‐(2‐chlorophenyl)‐3,4‐dimethylpent‐2‐ylium ion (both shown in Scheme 9 as D‐isomers) occurs through the same pathway.