Synthesis and molecular structures of 1‐chloro‐1‐silacyclopent‐2‐enes. Combination of 1,2‐hydroboration, 1,1‐organoboration and protodeborylation

The reaction of alkyn‐1‐yl(chloro)(methyl)vinyl‐ and alkyn‐1‐yl(chloro)(phenyl)‐vinylsilane with 9‐borabicyclo[3.3.1]nonane (9‐BBN) afforded selectively 1‐silacyclopent‐2‐ene derivatives containing a Si? Cl function, as a result of consecutive 1,2‐hydroboration and 1,1‐organoboration. Protodeborylation with acetic acid left the Si? Cl functions in various 1‐silacyclopent‐2‐enes untouched, whereas acetic acid in the presence of dipropylamine led to conversion of the Si? Cl into the Si? OAc function. New starting materials and all products were characterized in solution by multinuclear NMR spectroscopy (¹H, ¹¹B, ¹³C and ²⁹Si NMR), and the molecular structures of two 1‐silacyclopent‐2‐ene derivatives were determined by X‐ray analysis. The gas phase geometries of 1‐silacyclopent‐2‐enes were optimized by DFT calculations [B3LYP/6‐311 + G(d,p) level of theory], found to be in reasonable agreement with the results of the crystal structure determination, and NMR parameters were calculated at the same level of theory. Copyright © 2009 John Wiley & Sons, Ltd.     

1‐Silacyclopent‐2‐enes and 1‐silacyclohex‐2‐enes bearing functionally substituted silyl groups in 2‐positions. Novel electron‐deficient Si?H?B bridges

The reactions of alkyn‐1‐yl(vinyl)silanes R₂Si[C?C‐Si(H)Me₂]CH?CH₂ [R = Me (1a), Ph (1b)], Me₂Si[C?C‐Si(Br)Me₂]CH?CH₂ (2a), and of alkyn‐1‐yl(allyl)silanes R₂Si[C?C‐Si(H)Me₂]CH₂CH?CH₂ (R = Me (3a), R = Ph (3b)] with 9‐borabicyclo[3.3.1]nonane in a 1:1 ratio afford in high yield the 1‐silacyclopent‐2‐ene derivatives 4a, b and 5a, and the 1‐silacyclohex‐2‐ene derivatives 6a, b, respectively, all of which bear a functionally substituted silyl group in 2‐position and the boryl group in 3‐position. This is the result of selective intermolecular 1,2‐hydroboration of the vinyl or allyl group, followed by intramolecular 1,1‐organoboration of the alkynyl group. In the cases of 4a, b, potential electron‐deficient Si? H? B bridges are absent or extremely weak, whereas in 6a,b the existence of Si? H? B bridges is evident from the NMR spectroscopic data (¹H, ¹¹B, ¹³C and ²⁹Si NMR). The molecular structure of 4b was determined by X‐ray analysis. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis and structure of novel spirosilanes. Combination of 1,2‐hydroboration and 1,1‐organoboration

The reaction of tetra(alkyn‐1‐yl)silanes Si(C?C‐R¹)₄ 1 [R¹ = ^tBu ( a ), Ph ( b ), C₆H₄‐4‐Me ( c )] with 9‐borabicyclo[3.3.1]nonane (9‐BBN) in a 1:2 ratio affords the spirosilane derivatives 5a – c as a result of twofold intermolecular 1,2‐hydroboration, followed by twofold intramolecular 1,1‐organoboration. Intermediates 3a–c , in which two alkenyl‐ and two alkyn‐1‐yl groups are linked to silicon, were identified by NMR spectroscopy. The molecular structure of the spiro compound 5c was determined by X‐ray analysis, and the solution‐state structures of products and intermediates follow conclusively from the consistent NMR spectroscopic data sets (¹H, ¹¹B, ¹³C and ²⁹Si NMR). Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis of 1‐silacyclopent‐2‐ene derivatives using 1,2‐hydroboration, 1,1‐organoboration and protodeborylation

The reaction of di(alkyn‐1‐yl)vinylsilanes R¹(H₂C═CH)Si(C≡C―R)₂ (R¹ = Me ( 1 ), Ph ( 2 ); R = Bu (a), Ph (b), Me₂HSi (c)) at 25°C with 1 equiv. of 9‐borabicyclo[3.3.1]nonane (9‐BBN) affords 1‐silacyclopent‐2‐ene derivatives ( 3a , 3b , 3c , 4a , 4b ), bearing one Si―C≡C―R function readily available for further transformations. These compounds are formed by consecutive 1,2‐hydroboration followed by intramolecular 1,1‐carboboration. Treated with a further equivalent of 9‐BBN in benzene they are converted at relatively high temperature (80–100°C) into 1‐alkenyl‐1‐silacyclopent‐2‐ene derivatives ( 5a , 5b 6a , 6b ) as a result of 1,2‐hydroboration of the Si―C≡C―R function. Protodeborylation of the 9‐BBN‐substituted 1‐silacyclopent‐2‐ene derivatives 3 , 4 , 5 , 6 , using acetic acid in excess, proceeds smoothly to give the novel 1‐silacyclopent‐2‐ene ( 7 , 8 , 9 , 10 ). The solution‐state structural assignment of all new compounds, i.e. di(alkyn‐1‐yl)vinylsilanes and 1‐silacyclopent‐2‐ene derivatives, was carried out using multinuclear magnetic resonance techniques (¹H, ¹³C, ¹¹B, ²⁹Si NMR). The gas phase structures of some examples were calculated and optimized by density functional theory methods (B3LYP/6‐311+G/(d,p) level of theory), and ²⁹Si NMR parameters were calculated (chemical shifts δ²⁹Si and coupling constants ⁿJ(²⁹Si,¹³C)). Copyright © 2014 John Wiley & Sons, Ltd.     

Boryl‐substituted 1‐silacyclobutenes. Formation and molecular structure

The 1,2‐hydroboration of the chloro(hexyn‐1‐yl)‐ ( 1a ) and chloro(phenylethyn‐1‐yl)diphenylsilanes ( 1b ) with 9‐borabicyclo[3.3.1]nonane afforded selectively the alkenylsilanes 2a, b , in which the boryl and the silyl groups are linked to the same olefinic carbon atom. In case of 2a , treatment with phenylethynyl lithium gave a mixture of the alkyn‐1‐ylborate 3a and the alkenyl(phenylethynyl)diphenylsilanes 4a . In the case of 2b , only the alkyn‐1‐ylsilane 4b was identified as an intermediate. Both 4a, b slowly rearranged by intramolecular 1,1‐vinylboration into the silacyclobutenes 5a, b . The intermediates were characterized by ¹H, ¹¹B, ¹³C and ²⁹Si NMR spectroscopy in solution, and the molecular structure of the 1‐silacyclobutene 5a was determined by X‐ray analysis. The gas phase geometries of model molecules corresponding to 5a were optimized by MO calculations using DFT methods [B3LYP/6‐311 + G(d,p) level of theory], found to be in reasonable agreement with the results of the crystal structure determination, and NMR parameters were calculated at the same level of theory. Copyright © 2006 John Wiley & Sons, Ltd.     

Imino‐Bridged Bisphosphaalkenes (2,4‐Diphospha‐3‐azapentadienes)

Deprotonation of aminophosphaalkenes (RMe₂Si)₂C?PN(H)(R′) (R=Me, iPr; R′=tBu, 1‐adamantyl (1‐Ada), 2,4,6‐tBu₃C₆H₂ (Mes*)) followed by reactions of the corresponding Li salts Li[(RMe₂Si)₂C?P(M)(R′)] with one equivalent of the corresponding P‐chlorophosphaalkenes (RMe₂Si)₂C?PCl provides bisphosphaalkenes (2,4‐diphospha‐3‐azapentadienes) [(RMe₂Si)₂C?P]₂NR′. The thermally unstable tert‐butyliminobisphosphaalkene [(Me₃Si)₂C?P]₂NtBu ( 4 a ) undergoes isomerisation reactions by Me₃Si‐group migration that lead to mixtures of four‐membered heterocyles, but in the presence of an excess amount of (Me₃Si)₂C?PCl, 4 a furnishes an azatriphosphabicyclohexene C₃(SiMe₃)₅P₃NtBu ( 5 ) that gave red single crystals. Compound 5 contains a diphosphirane ring condensed with an azatriphospholene system that exhibits an endocylic P?C double bond and an exocyclic ylidic P⁽⁺⁾? C^(?)(SiMe₃)₂ unit. Using the bulkier iPrMe₂Si substituents at three‐coordinated carbon leads to slightly enhanced thermal stability of 2,4‐diphospha‐3‐azapentadienes [(iPrMe₂Si)₂C?P]₂NR′ (R′=tBu: 4 b ; R′=1‐Ada: 8 ). According to a low‐temperature crystal‐structure determination, 8 adopts a non‐planar structure with two distinctly differently oriented P?C sites, but ³¹P NMR spectra in solution exhibit singlet signals. ³¹P NMR spectra also reveal that bulky Mes* groups (Mes*=2,4,6‐tBu₃C₆H₂) at the central imino function lead to mixtures of symmetric and unsymmetric rotamers, thus implying hindered rotation around the P? N bonds in persistent compounds [(RMe₂Si)₂C?P]₂NMes* ( 11 a , 11 b ). DFT calculations for the parent molecule [(H₃Si)₂C?P]₂NCH₃ suggest that the non‐planar distortion of compound 8 will have steric grounds.     

1,1‐Ethylboration of alkyn‐1‐yl‐chloro(methyl)silanes: alkenes with chloro(methyl)silyl and diethylboryl groups in cis positions

The 1,1‐ethylboration of alkyn‐1‐yl‐chloro(methyl)silanes, Me₂Si(Cl)? C?C? R ( 1 ) and Me(H)Si(Cl)? C?C? R ( 2 ) [R = Bu ( 2a ), CH₂NMe₂ ( 2b )] requires harsh reaction conditions (up to 20 days in boiling triethylborane), and leads to alkenes in which the boryl and silyl groups occupy cis ((E)‐isomers: 3a , 3b , 5a , 5b ) or trans positions ((Z)‐isomers in smaller quantities: 4b and 6b ). The alkenes are destabilized in the presence of SiH(Cl) and CH₂NMe₂ units ( 5b , 6b ). NMR data indicate hyper‐coordinated silicon by intramolecular N? Si coordination in 3b and 5b , by which, at the same time, weak Si? Cl? B bridges are favoured. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis of 4‐silaspiro[3.4]octa‐1,5‐diene derivatives: hybrid spiro compounds

Trialkynyl(vinyl)silanes CH₂?CH? Si(C?C? R)₃ (R = Bu, Ph, p‐tolyl) were prepared and treated with 9‐borabicyclo[3.3.1]nonane (9‐BBN). Consecutive 1,2‐hydroboration and intramolecular 1,1‐carboboration reactions (each requires different reaction conditions) were studied. 1,2‐Hydroboration of the Si? vinyl group takes place at ambient temperature (23°C in tetrahydrofuran), followed by intramolecular 1,1‐vinylboration to give 1‐silacyclopent‐2‐ene derivatives, bearing still two alkynyl functions at the silicon atom. Further treatment with a second equivalent of 9‐BBN affords 1‐alkenyl‐1‐(alkynyl)‐1‐silacyclopent‐2‐ene derivatives. These undergo intramolecular 1,1‐vinylboration to give 4‐silaspiro[3.4]octa‐1,5‐dienes bearing the boryl groups at 2 and 6 positions. Protodeborylation of all new compounds (intermediates and final products) using acetic acid in slight excess afforded corresponding silanes including spirosilanes. All compounds were characterized using multinuclear NMR spectroscopy (¹H, ¹¹B, ¹³C, ²⁹Si) in solution state. Solid‐state structures for one of the trialkynyl(vinyl)silanes (R = p‐tolyl) and one of the 1‐silacyclopent‐2‐ene derivatives (R = Ph) were confirmed using X‐ray diffraction. Copyright © 2015 John Wiley & Sons, Ltd.     

Difunctionalized {closo‐1‐CB11} Clusters: 1‐ and 2‐Amino‐12‐ethynylcarba‐closo‐dodecaborates

Carba‐closo‐dodecaborate anions with two functional groups have been synthesized via a simple two‐step procedure starting from monoamino‐functionalized {closo‐1‐CB₁₁} clusters. Iodination at the antipodal boron atom provided access to [1‐H₂N‐12‐I‐closo‐1‐CB₁₁H₁₀]^? ( 1 a ) and [2‐H₂N‐12‐I‐closo‐1‐CB₁₁H₁₀]^? ( 2 a ), which have been transformed into the anions [1‐H₂N‐12‐RC?C‐closo‐1‐CB₁₁H₁₀]^? (R=H ( 1 b ), Ph ( 1 c ), Et₃Si ( 1 d )) and [2‐H₂N‐12‐RC?C‐closo‐1‐CB₁₁H₁₀]^? (R=H ( 2 b ), Ph ( 2 c ), Et₃Si ( 2 d )) by microwave‐assisted Kumada‐type cross‐coupling reactions. The syntheses of the inner salts 1‐Me₃N‐12‐RC?C‐closo‐1‐CB₁₁H₁₀ (R=H ( 1 e ), Et₃Si ( 1 f )) and 2‐Me₃N‐12‐RC?C‐closo‐1‐CB₁₁H₁₀ (R=H ( 2 e ), Et₃Si ( 2 f )) are the first examples for a further derivatization of the new anions. All {closo‐1‐CB₁₁} clusters have been characterized by multinuclear NMR and vibrational spectroscopy as well as by mass spectrometry. The crystal structures of Cs 1 a , [Et₄N] 2 a , K 1 b , [Et₄N] 1 c , [Et₄N] 2 c , 1 e , and [Et₄N][1‐H₂N‐2‐F‐12‐I‐closo‐1‐CB₁₁H₉]?0.5 H₂O ([Et₄N ]4 a ?0.5 H₂O) have been determined. Experimental spectroscopic data and especially spectroscopic data and bond properties derived from DFT calculations provide some information on the importance of inductive and resonance‐type effects for the transfer of electronic effects through the {closo‐1‐CB₁₁} cage.     

A novel 4‐methylene‐3‐borahomoadamantane: 1,1‐organoboration of an alkyn‐1‐ylsilane using 1‐boraadamantane

1,1‐Dibromo‐2,2‐bis(trimethylsilylethynyl)ethene ( 2 ) reacts with two equivalents of 1‐boraadamantane ( 1 ) by 1,1‐organoboration of both trimethylsilylethynyl groups to give a triene 3 bearing two 4‐methylene‐3‐borahomoadamantane moieties in terminal positions. The triene was characterized by one‐ and two‐dimensional ¹H, ¹¹B, ¹³C and ²⁹Si NMR spectroscopy in solution and X‐ray structural analysis in the solid state. The planes of the C double bond are strongly twisted against each other as a result of the bulky substituents, and the surroundings of the boron atoms deviate from the ideal trigonal planar geometry owing to the tension in the tricyclic frameworks. Copyright © 2006 John Wiley & Sons, Ltd.     

Diselenastanna‐, ‐sila‐ and ‐carbacycles with an annelated dicarba‐closo‐dodecaborane(12) unit

The reactions of the 1,2‐diselenolato‐1,2‐dicarba‐closo‐dodecaborane(12) dianion 1 with diorganoelement(IV) dichlorides (Ph₂CCl₂, Me₂SiCl₂, Ph₂SiCl₂, Me₂SnCl₂, Ph₂SnCl₂) gave novel five‐member heterocycles along with other products. The molecular structures of the five‐member rings containing CPh₂ ( 2 ) and SnPh₂ ( 9 ) moieties between the selenium atoms were determined by X‐ray analyses. In the case of the chlorosilanes, the analogous five‐member ring containing the SiPh₂ unit ( 4 ) could be identified in mixtures. The expected reaction was accompanied by rearrangement leading to formation of another five‐member ring 6 containing the Ph₂Si? Se? Se moiety. Oxidative addition of the five‐member heterocycles containing tin ( 7, 9 ) to ethene‐bis(triphenylphosphane)platinum(0) gave at low temperature the bis(triphenylphosphane)platinum(II) complexes 12 and 13 , where the Pt(PPh₃)₂ fragment had been inserted into one of the Sn? Se bonds. Extensive decomposition of these complexes was observed above ? 20 °C. The proposed solution‐state structures of the new compounds are supported by multinuclear magnetic resonance data (¹H, ¹¹B, ¹³C, ²⁹Si, ³¹P, ⁷⁷Se, ¹¹⁹Sn and ¹⁹⁵Pt NMR). Copyright © 2007 John Wiley & Sons, Ltd.     

Ammonolysis of 1,2‐Bis[dichloro(methyl)silyl]ethane. On the Structure of 1,3,6,8‐Tetramethyl‐2,7,11,12‐tetraaza‐1,3,6,8‐tetrasila‐tricyclo[6.2.1.13,6]‐dodecane

Ammonolysis of 1,2‐bis[dichloro(methyl)silyl]ethane afforded a crystalline tricyclic silazane along with polymeric material. The crystalline material could be isolated in pure state. It was analyzed by ¹H, ¹³C, ¹⁵N and ²⁹Si NMR spectroscopy in solution, by ¹³C, ¹⁵N and ²⁹Si MAS NMR spectroscopy in the solid state, as well as by single‐crystal and powder X‐ray diffraction. The title compound exists as a single isomer in solution, whereas in the solid state the presence of several modifications is indicated, in particular by the solid‐state MAS NMR spectra.     

固相β-环糊精包结物诱导7-羟基-2-甲氧基-2-甲基色满的不对称合成

研究了室温下间苯二酚和甲基乙烯基酮分别与β-环糊精（ β-CD）形成包结物后的几种不同固相反应,结果表明包结物A（间苯二酚/β-CD）与包结物B（甲基乙烯基酮/β-CD）反应能够很好地得到目的产物,产率及ee值分别为82.8%和78.4%;间苯二酚与包结物B反应仅得到低光学活性产物（ee值为19.5%）;包结物A与甲基乙烯基酮反应却没有得到手性目的产物。以熔点、X-粉末衍射、固相核磁碳谱及ROESY多种方法对所形成的包结物进行了表征,包结物中主客体的比例（1：1）通过¹H NMR (400 MHz)得以确定,文章对固相环加成反应的机制也进行了初步探讨。     

The New λ6Si‐Silicate Dianion [Si(NCO)6]2−: Synthesis and Structural Characterization of [K(18‐crown‐6)]2[Si(NCO)6]

The λ⁶Si‐silicate [K(18‐crown‐6)]₂[Si(NCO)₆] ( 10 ) was synthesized by treatment of Si(NCO)₄ with KNCO in the presence of 18‐crown‐6. Compound 10 (SiN₆ skeleton) is the first example of a hexa(cyanato‐N)silicate. It was characterized by solid‐state and solution NMR spectroscopy, and the acetonitrile solvate 10· 2CH₃CN was studied by single‐crystal X‐ray diffraction. To differentiate between the two isomeric [Si(NCO)₆]^2? and [Si(OCN)₆]^2? dianions, computational studies were performed.     

Unexpected Spiroproducts from the Reaction of N‐Benzoylglycine with Ortho‐Formylbenzoic Acids −3,5′‐Dioxo‐2′‐Phenyl‐1,3‐Dihydrospiro[Indene‐2,4′‐[1,3]Oxazol]‐1‐yl Acetates: Establishments of Their Structure

This paper describes a method of preparation of new 3,5′‐dioxo‐2′‐phenyl‐1,3‐dihydrospiro[indene‐2,4′‐[1,3]oxazol]‐1‐yl acetate and its 5‐chloro‐ and bromoderivatives as products of interaction of N‐benzoylglycine (hippuric acid) with corresponding ortho‐formylbenzoic acids. The reaction carried out in acetic anhydride media in the presence of piperidine as catalyst. The novel spirocompounds were purified by column chromatography from multicomponent reaction mixtures. The composition of the spiro‐products was confirmed by C, H, N element analysis. The structure was established by IR, MS, ¹H‐ and ¹³C‐NMR analysis including COSY ¹H‐¹³C experiments.     

Vacuum‐UV Irradiation‐Based Formation of Methyl‐Si‐O‐Si Networks from Poly(1,1‐Dimethylsilazane‐co‐1‐methylsilazane)

The vacuum‐UV (VUV)‐induced conversion of commercially available poly(1,1‐dimethylsilazane‐co‐1‐methylsilazane) into methyl‐Si‐O‐Si networks was studied using UV sources at wavelengths around 172, 185, and 222 nm, respectively. Time‐of‐flight secondary ion mass spectroscopy (TOF‐SIMS), X‐ray photo electron spectroscopy (XPS), and Fourier transform infrared (FTIR) measurements, as well as kinetic investigations, were carried out to elucidate the degradation process. First‐order kinetics were found for the photolytically induced decomposition of the Si? NH‐Si network, the subsequent formation of the methyl‐Si‐O‐Si network and the concomitant degradation of the Si? CH₃ bond, which were additionally independent of the photon energy above a threshold of about 5.5 eV (225 nm). The kinetics of these processes were, however, dependent on the dose actually absorbed by the layer and, in the case of Si‐O‐Si formation, additionally on the oxygen concentration. The release of ammonia and methane accompanied the conversion process. Quantum‐chemical calculations on methyl substituted cyclotetrasilazanes as model compounds substantiate the suggested reaction scheme. Layers <100 nm in thickness based on mixtures of poly(1,1‐dimethylsilazane‐co‐1‐methylsilazane) and perhydropolysilazane (PHPS) were coated onto polyethylene terephthalate (PET) foils by a continuous roll to roll process and cured by VUV irradiation by using wavelengths <200 nm and investigated for their O₂ and water vapor‐barrier properties. It was found that the resulting layers displayed oxygen and water vapor transmission rates (OTR and WVTR, respectively) of <1 cm³ m^?2 d^?1 bar^?1 and <4 g m^?2 d^?1, respectively.     

Metallacyclopentadienes and related heterocycles via 1,1‐organoboration of alkyn‐1‐ylmetal compounds

Metallacyclopentadienes (metalloles) containing M = Si, Ge, Sn, Pb, Ti, Pt can be prepared by 1,1‐organoboration of alkyn‐1‐ylmetal compounds L_nM CC R¹(R¹ = H, alkyl, aryl, silyl, etc; L depends on M, and can be hydrogen, alkyl, aryl, Cl, Br, amino groups, a chelating diphosphane, and one or more L can be again alkynyl groups). These reactions proceed via activation of the M C bond(s) by an electron‐deficient triorganoborane BR₃ (R = alkyl, aryl; non‐cyclic, monocyclic, bicyclic, and tricyclic boranes), at first intermolecular and then intramolecular. In the course of these reactions, the M C bonds are cleaved, zwitterionic alkynylborate‐like intermediates are formed, in which the metal‐containing fragments are coordinated side‐on to the CC bonds. In most cases, the 1,1‐organoboration reactions tolerate various functional groups at the alkyne as well as at the metal. The characterization of intermediates and final products by X‐ray structural analysis and by multinuclear magnetic resonance spectroscopy (NMR) is documented and described. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:188–208, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20222     

Synthesis,structure and biological activity of new 6,6‐dimethyl‐2‐oxo‐4‐{2‐[5‐organylsilyl(germyl)]furan(thiophen)‐2‐yl}vinyl‐5,6‐dihydro‐2H‐pyran‐3‐carbonitriles

New 6,6‐dimethyl‐2‐oxo‐4‐{2‐[5‐alkylsilyl(germyl)]furan(thiophen)‐2‐yl}vinyl‐5,6‐dihydro‐2H‐pyran‐3‐carbonitriles (IC₅₀: 1–6 µg ml^?1) have been prepared by the condensation of corresponding silicon‐ and germanium‐containing furyl(thienyl)‐2‐carbaldehydes with 3‐cyano‐4,6,6‐trimethyl‐5,6‐dihydropyran‐2‐one using piperidine acetate as a catalyst. The obtained carbonitriles were identified using NMR (¹H, ¹³C and ²⁹Si) spectroscopy and GC‐MS. The structure of 6,6‐dimethyl‐2‐oxo‐4‐[2‐(5‐trimethylsilyl)thiophen‐2‐yl]‐5,6‐dihydro‐2H‐pyran‐3‐carbonitrile was studied using X‐ray diffractometry. The influences of the heterocycle and the structure of the organoelement substituent on cytotoxicity and on matrix metalloproteinase inhibition have been studied. Copyright © 2015 John Wiley & Sons, Ltd.     

One‐Pot Synthesis of 4‐(Alkylamino)‐1‐(arylsulfonyl)‐3‐benzoyl‐1,5‐ dihydro‐5‐hydroxy‐5‐phenyl‐2H‐pyrrol‐2‐ones via a Multicomponent Reaction

An effective route to novel 4‐(alkylamino)‐1‐(arylsulfonyl)‐3‐benzoyl‐1,5‐dihydro‐5‐hydroxy‐5‐phenyl‐2H‐pyrrol‐2‐ones 10 is described (Scheme 2). This involves the reaction of an enamine, derived from the addition of a primary amine 5 to 1,4‐diphenylbut‐2‐yne‐1,4‐dione, with an arenesulfonyl isocyanate 7 . Some of these pyrrolones 10 exhibit a dynamic NMR behavior in solution because of restricted rotation around the C? N bond resulting from conjugation of the side‐chain N‐atom with the adjacent α,β‐unsaturated ketone group, and two rotamers are in equilibrium with each other in solution ( 10 ? 11 ; Scheme 3). The structures of the highly functionalized compounds 10 were corroborated spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS), by elemental analyses, and, in the case of 10a , by X‐ray crystallography. A plausible mechanism for the reaction is proposed (Scheme 4).     

Multiple Pentafluorophenylation of 2,2,3,3,5,6,6‐Heptafluoro‐3,6‐dihydro‐2H‐1,4‐oxazine with an Organosilicon Reagent: NMR and DFT Structural Analysis of Oligo(perfluoroaryl) Compounds

The reagent Me₃Si(C₆F₅) was used for the preparation of a series of perfluorinated, pentafluorophenyl‐substituted 3,6‐dihydro‐2H‐1,4‐oxazines ( 2 – 8 ), which, otherwise, would be very difficult to synthesize. Multiple pentafluorophenylation occurred not only on the heterocyclic ring of the starting compound 1 (Scheme), but also in para position of the introduced C₆F₅ substituent(s) leading to compounds with one to three nonafluorobiphenyl (C₁₂F₉) substituents. While the tris(pentafluorophenyl)‐substituted compound 3 could be isolated as the sole product by stoichiometric control of the reagent, the higher‐substituted compounds 5 – 8 could only be obtained as mixtures. The structures of the oligo(perfluoroaryl) compounds were confirmed by ¹⁹F‐ and ¹³C‐NMR, MS, and/or X‐ray crystallography. DFT simulations of the ¹⁹F‐ and ¹³C‐NMR chemical shifts were performed at the B3LYP‐GIAO/6‐31++G(d,p) level for geometries optimized by the B3LYP/6‐31G(d) level, a technique that proved to be very useful to accomplish full NMR assignment of these complex products.