Regiochemical and stereochemical studies on halocyclization reactions of unsaturated sulfides
摘要:
The regiochemistry and stereochemistry for the halocyclization reactions of unsaturated benzyl sulfides have been examined as a function of tether length, type of unsaturation (carbon-carbon double bond versus carbon-carbon triple bond), substituents, and halogenating agent. Alkenyl sulfides were found to react with iodine or bromine at room temperature to give five-membered ring cycloadducts exclusively over those having four-membered rings, while for larger systems, six-membered ring products are formed preferentially over their five-membered ring isomers and exclusively over the seven-membered ring adducts. The endo- versus exo-regioselectivity of these alkenyl sulfide ring closures most likely reflects the difference in thermodynamic stabilities of the beta-halo sulfide cycloadducts, which are able to equilibrate via a common episulfonium intermediate. The efficiency of the cyclization process markedly drops off for these alkenyl sulfides as the tether length increases beyond four intervening carbon centers. Thus, while the halogenations of 3-butenyl sulfides and 4-pentenyl sulfides give high yields of cycloadducts, those of 5-hexenyl sulfides afford only small amounts of cyclized products and large quantities of acyclic dibromides. Conversely the reactions of acetylenic sulfides with iodine give uniformly high yields and regiochemical control regardless of the tether length. Thus, 3-butynyl and 4-pentynyl sulfides cyclize cleanly to the five-membered ring while 5-hexynyl sulfides give exclusively the six-membered ring, The products arising from these alkynyl sulfide ring closures are believed to be formed under kinetic control. The methodology has been applied to the synthesis of unusual bicyclic beta-lactams related to the penicillin family of antibiotics.
The present description relates to fused polycyclic 2-pyridinone compounds and forms and pharmaceutical compositions thereof and methods of using such compounds, forms or compositions thereof for treating or ameliorating a wild-type or drug-resistant form of N. gonorrhoeae or N. meningitides. A compound of Formula (la), Formula (lb) or Formula (Ic), or a form thereof, wherein the dashed lines represent one or more double bonds optionally present where allowed by available valences.
[EN] ANTIBACTERIAL COMPOUNDS AND METHODS FOR USE<br/>[FR] COMPOSÉS ANTIBACTÉRIENS ET PROCÉDÉS POUR LEUR UTILISATION
申请人:PTC THERAPEUTICS INC
公开号:WO2013033228A1
公开(公告)日:2013-03-07
The present description relates to compounds and forms and pharmaceutical compositions thereof and methods for use thereof to treat or ameliorate bacterial infections caused by wild-type and multi-drug resistant Gram-negative and Gram-positive pathogens. The present description further relates to a compound having activity toward wild-type and MDR bacteria. The present description also relates to a compound having activity against quinolone-resistant Gram-negative strains (including MDR strains) as well as antibacterial activity to MDR resistant Gram-positive pathogens (including MRSA strains).
Electrophilic Cleavage of Cyclopropylmethystannanes: An Experimental Comparison of σ−σ and σ−π Conjugation
作者:Andrew J. Lucke、David J. Young
DOI:10.1021/jo047822p
日期:2005.4.1
Cyclopropylmethyltrimethylstannanes undergo electrophiliccyclopropanecleavage in chloroform with simple inorganic electrophiles (H+, SO2, I2) in a homologous reaction to the SE‘ cleavage of allylic stannanes. The σ−σ conjugation between the carbon−tin bond and cyclopropane orbitals observed spectroscopically in the parent cyclopropylmethyltrimethylstannane is responsible for a rate enhancement of
环丙基甲基三甲基锡烷酮与简单的无机亲电试剂(H +,SO 2,I 2)在氯仿中进行亲电环丙烷裂解,与烯丙基锡烷的S E '裂解发生同源反应。在母体环丙基甲基三甲基锡烷中通过光谱观察到的碳-锡键与环丙烷轨道之间的σ-σ共轭可提高ca的速率。相对于可比较的烷基锡烷,10 2趋向碘解。但是,该加速度远小于约1。10 9烯丙基锡烷中相应的σ-π共轭提供的倍数速率增强。甲醇-锡配位似乎减少了金属的活化作用,从而促进了在环丙烷裂变中用酸和碘进行甲基裂解。降低的σ-σ共轭也可以解释与三甲基锡对应物相比环丙基三苯基锡烷的反应性降低。在促进烯丙基锡烷的相应反应的条件下,环丙基甲基锡烷不经过合成有用的醛加成。
ANTIBACTERIAL COMPOUNDS AND METHODS FOR USE
申请人:PTC THERAPEUTICS, INC.
公开号:US20150038438A1
公开(公告)日:2015-02-05
The present description relates to compounds and forms and pharmaceutical compositions thereof and methods for use thereof to treat or ameliorate bacterial infections caused by wild-type and multi-drug resistant Gram-negative and Gram-positive pathogens.