Terminally Dimetallated N,N′‐Dimethylpiperazines with Doubly Spirocyclic Structures

Dilithiated N,N′‐dimethyl‐piperazine, LiCH₂N(CH₂CH₂)₂ NCH₂Li ( 2 ) was prepared by transmetallation of N,N′‐bis(trimethylstannylmethyl)‐piperazine ( 1 ) with ⁿBuLi and was isolated as a highly pyrophoric yellowish powder in high yield. Compound 2 was characterized by elemental analysis and was reacted as difunctional aminomethylating reagent with dialkyl‐earth metal chlorides, R₂MCl (M = Al, Ga; R = Me, ^tBu) which resulted in the formation of spirocyclic adducts of N,N′‐bis(dialkylmetallamethyl)‐piperazine and unreacted dialkylmetal chlorides, [(Me₂AlCl)Me₂AlCH₂N(CH₂CH₂)₂NCH₂AlMe₂(ClAlMe₂)] ( 3 ) and [(^tBu₂GaCl)^tBu₂GaCH₂N(CH₂CH₂)₂NCH₂Ga^tBu₂(ClGa^tBu₂)] ( 4 ) with five‐membered rings. Compounds 1 , 3 and 4 were identified by NMR‐spectroscopy (¹H, ¹³C, ¹¹⁹Sn for 1 , ²⁷Al for 3 ), mass spectra (EI, for 1 ) and by crystal structure determinations.     

Dilithiated synthons: synthesis of cyclic ethers

Recent advances in the generation of dilithiated synthons by arene-catalyzed lithiation of the corresponding dichloro compounds in the presence of carbonyl compounds (Barbier-type reaction conditions) as the key step are described. Further cyclization of the generated diols under different reaction conditions affords a variety of mono-, bi-, and spirocyclic ethers.     

Synthesis of spiro[isoquinoline-4,4′-pyran]-3-imines

A method has been developed for the synthesis of 4-[2-(bromomethyl)phenyl] tetrahydro-2H-4-pyrancarbonitrile and a study was carried out on the reaction of this compound with primary amines, which, depending on the conditions, leads to either 4-[2-(R-aminomethyl)phenyl]tetrahydro-2H-4-pyrancarbonitriles or hydrobromides of 2-R-aryl-2,3,2,3,5,6-hexahydrospiro[isoquinoline-4(1H),4-pyran]-3-imines.Taras Shevchenko Kiev University, 252017 Kiev, Ukraine; e-mail: vkysil@mail.univ.kiev.ua. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1035–1041, August, 2000.     

具有岩兰烷基本结构的螺[4,5]癸多烯的合成

利用1,5-二甲基-6-亚甲基环己烯和2,4-二氧代戊酸甲酯的deMayo反应,经加成产物retro-benzilic acid重排,一步构成岩兰烷属螺环倍半萜类天然产物的基本碳架,通过对螺环上的多种官能团进行化学修饰,合成一系列螺[4,5]癸多烯化合物.所合成的新化合物的化学结构均经IR,1H NMR及元素分析予以证实.     

Spirocyclic bisphenoxides of Ge,Zr, and Sn as catalysts for ring-expansion polymerizations of l- and meso-lactide

Spirocyclic phenoxides of germanium, zirconium, and tin were prepared from 2,2′-dihydroxybiphenyl and 2,2′-dihydroxy-1,1′-binaphthyl. Ring-expansion polymerizations of l -lactide are mainly studied at 160 or 180 °C. The reactivity of the catalysts increases in the order: Zr < Ge < Sn. Regardless of catalyst, the weight-average molecular weights (M_w) never exceed 50,000 g mol⁻¹. The resulting poly(l -lactide)s are optically pure and have a cyclic architecture. Decreasing temperature and time favor formation of even-numbered cycles, and at 102° cyclics, almost free of odd-numbered rings are obtained. Analogous polymerizations of meso-lactide give similar results >120 °C, but different results at 100 or 80 °C. Surprisingly, bell-shaped narrow molecular weight distributions are obtained <140 °C, resembling the pattern of living polymerizations found for alcohol-initiated polymerizations. An unusual transesterification mechanism yielding narrow distributions of odd-numbered cycles is discovered too. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2730–2738     

Syntheses and Crystal Structures of Two Tin(Ⅳ) Complexes with Aminosilane Bearing Ligand

Aminosilane bearing bulky substituents on nitrogen: LH2(L=Me2Si(NDipp-)2 , Dipp=2,6-diisopropylphenyl) was reacted with BuLi in toluene. The resulting bulky chelating dianion Me2Si(NDipp-)2 was used to synthesize the unusual spirocyclic heterotriatomic complex [Me2Si(NDipp)2]2Sn (1) by its reaction with SnCl4 and the bulky heterotriatomic complex Me2Si(NDipp)2SnPh2 (2) with Ph2SnCl2.1 belongs to the monoclinic system, space group P21/n with a=13.193(2), b=20.663(3), c=20.403(3), β=99.954(2)o, V=5478.3(15)3 , C55H85.5N4Si2Sn, Mr=977.64, Z=4, Dc=1.185Mg/m3 , μ(MoKα)=0.547mm-1 , F(000)=2086, S=1.000, the final R=0.0614 and wR=0.1322 for 14446 observed reflections (I2σ(I)) and R=0.0797 and wR=0.1456 for all data. 2 belongs to the triclinic system, space group Pī with a=10.36(15), b=13.204(7), c=14.363(7), α=90.214(10), β=106.182(7), γ=109.854(8)o, V=1764.4(15)3 , C38H50N2SiSn, Mr=681.58, Z=2, Dc=1.283 Mg/m3 , μ(MoKα)=0.785 mm-1 , F(000)=712, S=1.002, the final R=0.0498 and wR=0.0955 for 7533 observed reflections (I2σ(I)) and R=0.0676 and wR=0.1018 for all data. In the structure of 1, the tin atom is located in the spirocyclic center of the two fused four-membered SnN 2 Si rings. The two complexes were characterized by 1H NMR, elemental analysis, and single-crystal X-ray structural analysis.     

Isocyanide‐Based Multicomponent Reactions: Concise Synthesis of Spirocyclic Oxindoles with Molecular Complexity by Using a [1,5]‐Hydrogen Shift as the Key Step

A concise multicomponent reaction of isocyanide, α‐substituted allenoate, and methyleneindolinone has been disclosed. This protocol provides a fast and straightforward approach to synthesize unusual tricyclic oxindoles in an efficient and atom‐economic manner. Mechanistically, the present cycloaddition may proceed through a cascade sequence involving double Michael addition, double cyclization, double [1,5]‐hydrogen shift, and group migration. The introduction of a special alkyl group to the allenoate is believed to play a key role in the cascade reaction. This method also features a broad substrate scope, which is particularly useful for the delivery of a large number of compounds.     

Synthesis,Structure and Antimicrobial Activity of 2-Phenyl-4H-spiro[benzo[e][1,4,2]oxaza- phosphinine-3,3′-indolin]-2′-one 2-oxide

A novel spiro-compound(C20 H15 N2 O3 P) has been synthesized and characterized by means of IR and 1H NMR. Its crystal structure was determined by X-ray diffractometry. The crystal belongs to the monoclinic system, space group P21 /c with a = 9.1628(7), b = 12.9490(7), c = 15.7898(11), β = 103.952(8)o, Mr = 36.08, V = 1818.2(2)3, Z = 4, Dc = 1.382 g/cm3, F(000) = 788, μ = 0.179 mm-1, R = 0.0701 and wR = 0.1513. The preliminary biological test showed that the title compound has activities against Escherichia coli, S.albus, Bacillus subtilis, Staphylocc- ocusaureus and Micrococcus tetragenus with MIC to be 0.038, 0.038, 0.075, 2.48, and 0.15 mg/mL, respectively.     

萜品油烯的DeMayo光环加成产物的反应研究

通过萜品油烯和2，6-二氧代戊酸甲酯的de Mayo反应，使[2 + 2]环加成产物 3-6经retro-aldol重排，开环生成取代环己烯7和12。在不同反应介质中对开环产 物进行再环合，并对其反应机理进行研究。在碱性条件下，经分子内Claisen缩合 反应形成螺环化合物；以对甲本碘酸为催化剂的环合，除生成正常的Claisen缩合 产物以外，7和12均发生烯键亲核加成反应，生成具有二环[3.3.1]结构的桥环化合 物9-11和二环[3.2.1]结构的桥环化合物16-18。所得新化合物的化学结构均经IR, ~1H NMR，~(13)C NMR及元素分析予以确定。     

Mechanistic Insights into the Post‐Cyclization Isomerization in Gold‐Catalyzed 7‐exo‐dig‐Hydroarylations

The subsequent double‐bond isomerization in the synthesis of dibenzocycloheptenes and their heteroaromatic analogues was investigated. In the case of biphenyls, a basic additive completely prevented an isomerization to the thermodynamic product. With electron‐rich intramolecular heteroaromatic nucleophiles, the isomerization was still observed, but the kinetic product can be obtained by careful control of the reaction times in most cases. Mechanistic studies demonstrated that a slow isomerization is also possible with the gold catalyst at elevated temperatures, but much faster isomerization rates were observed with acidic additives. An observed initiation period for the gold‐catalyzed isomerization indicates that not the homogenous catalyst, but a decomposition product of it may be the catalytically active species.