四氟乙烯齐聚体的反应——ⅤⅢ.2-(1''''-烯丙氧基)四氟乙基-3-三氟甲基-3-五氧乙基全氟-1-戊烯分子内[2+2]环化加成反应

氟烯烃分子间的[2+2]环化加成及氟烯烃和烯基化合物分子间的[2+2]环加成早有很好的总结。近年来,比较复杂的氟烯分子间的环化加成及其反应机理的研究也有很好的介绍,但有关分子的内[2+2]环化加成却很少报道。Brook 最近研究了1,3,4,5,6,7,8-     

邻醌与噁唑的光化[4+4]环加成反应

虽然[2+2]和[4+4]环加成反应都是光化学允许的,但[4+4]环加成远不及[2+2]反应普遍.已知的[4+4]环加成主要为蒽、萘、吡啶-2-酮和吡喃-2-酮衍生物的光化二聚以及它们与某些1,3-二烯的环加成.羰基化合物与烯烃一般发生[2+2]环加成(Peterno-B點hi反应).邻醌和α-二羰基化合物与富电子烯烃则已知可进行[2+2]或[4+2]的光化环加成反应,分别得到α-羰基氧杂环丁烷和1,4-二氧杂环己烯.但未知有光化[4+4]环加成反应.     

新型2-氧代-1,2,4-三唑并[3,2-d][1,5]苯并氧氮杂类稠杂环的合成

将取代色满酮 ( 1 )与芳肼反应生成的腙与 HNCO发生 [3 +2 ]环加成反应 ,加成产物 ( 2 )经氧化得到偕偶氮异氰酸酯 ( 3 ) .化合物 3在 HBF4 的催化下发生环化 -重排反应 ,得到新颖的三环系 2 -氧代 -1 ,2 ,4-三唑并[3 ,2 -d][1 ,5 ]苯并氧氮杂化合物 5 a～ 5 g     

新型2-氧代-1,2,4-三唑并[3,2-d][1,5]苯并氧氮杂类稠杂环的合成

将取代色满酮(1)与芳肼反应生成的腙与HNCO发生[3+2]环加成反应,加成产物(2)经氧化得到偕偶氮异氰酸酯(3).化合物3在HBF4的催化下发生环化-重排反应,得到新颖的三环系2-氧代-1,2,4-三唑并[3,2-d][1,5]苯并氧氮杂化合物5a～5g.     

新型2-氧代-1,2,4-三唑并[3,2-d][1,5]苯并氧氮杂(艹卓)类稠杂环的合成

将取代色满酮(1)与芳肼反应生成的腙与HNCO发生[3+2]环加成反应,加成产物(2)经氧化得到偕偶氮异氰酸酯(3).化合物3在HBF4的催化下发生环化-重排反应,得到新颖的三环系2-氧代-1,2,4-三唑并[3,2-d][1,5]苯并氧氮杂(艹卓 )化合物5a～5g.     

61-甲基-61-[12-(18-N-四氯邻苯二甲酰亚氨基)脱氢枞胺]-1,2-亚甲基富勒烯[60]的合成

以脱氢枞胺为原料,经氨基酰化、12位乙酰化、与对甲苯磺酰肼形成对甲苯磺酰腙衍生物,再通过卡宾中间体与C60进行[2+1]环加成反应合成了C60-脱氢枞胺衍生物。目标化合物经IR,UV-Vis,1H NMR,13C NMR,MALDI-TOF MS表征,所得化合物为[6,6]闭环结构C60加成产物。     

61-甲基-61-[12-(N,N-四氯邻苯二甲酰基)脱氢枞胺]-1,2-亚甲基富勒烯[60]的合成

以脱氢枞胺为原料,经氨基酰化、12位乙酰化、与对甲苯磺酰肼形成对甲苯磺酰腙衍生物,再通过卡宾中间体与C60进行[2+1]环加成反应合成了C60-脱氢枞胺衍生物。目标化合物经IR,UV-Vis,1H NMR,13C NMR,MALDI-TOF MS表征,所得化合物为[6,6]闭环结构C60加成产物。     

1,2-联烯亚砜和1,2-联烯砜的反应

1,2-联烯亚砜和1,2-联烯砜是重要的含硫联烯化合物.综述了1,2-联烯亚砜和1,2-联烯砜的亲核加成、亲电加成、Diels-Alder反应、1,3-偶极加成、[2+2]环加成等反应以及在天然产物中的应用.     

新型1,2,4-三唑并[3,2-d][1,5]苯并氧氮杂-2-酮的合成

取代苯并二氢吡喃 4 酮 ( 1)的芳腙在冰醋酸中与KNCO发生 [3 2 ]环加成反应 ,加成产物经KMnO4氧化开环得偕偶氮异氰酸酯 ( 3 ) .3在HBF4的催化下发生环化 -重排反应 ,合成得到一系列新型 6 7 5三环系 1,2 ,4 三唑并 [3 ,2 d] [1,5 ]苯并氧氮杂 2 酮 ( 5a～ 5g) .由X单晶衍射测定了化合物 5a的晶体结构     

新型1,2,4-三唑并[3,2-d][1,5]苯并氧氮杂(艹卓)-2-酮的合成

取代苯并二氢吡喃-4-酮(1)的芳腙在冰醋酸中与KNCO发生[3 2]环加成反应,加成产物经KMnO4氧化开环得偕偶氮异氰酸酯(3).3在HBF4的催化下发生环化-重排反应,合成得到一系列新型6-7-5三环系1,2,4-三唑并[3,2-d][1,5]苯并氧氮杂(艹卓)2-酮(5a～5g).由X单晶衍射测定了化合物5a的晶体结构.     

[2+2] Cycloaddition of chlorosulfonyl isocyanate to allenyl-sugar ethers

The direction and magnitude of asymmetric induction in the [2+2] cycloaddition of chlorosulfonyl isocyanate to 3-O-allenyl-α-d-xylofuranoses was investigated. It is shown that gem terminal dimethylallenes react more readily than methyl free congeners. The configuration of adducts was established by X-ray and CD-spectroscopy of alkylidene cephams. A stereochemical model of the transition state for the [2+2] cycloaddition of chlorosulfonyl isocyanate and allenyl ethers is proposed, based on the lowest energy conformation of the cumulene.     

Formal synthesis of (+/-)-peduncularine: use of the

[reaction: see text] The formal synthesis of the alkaloid (+/-)-peduncularine (1) was accomplished through the use of a [3 + 2] allylic silane annulation. The annulation of cyclohexadienyl silane 6 with chlorosulfonyl isocyanate followed by an in situ reduction provided bicyclic lactam 7. Conversion of this intermediate to 2 in three steps completed the formal synthesis of (+/-)-peduncularine.     

Synthesis of 4-membered ring alkaloid analogues via intramolecular [2+2] cycloaddition involving keteniminium salt intermediates

We have developed a very straightforward method for the synthesis of 4-membered ring alkaloid analogues via intramolecular [2+2] cycloadditions. This involves the cyclization of a keteniminium salt in which an alkene is linked by the nitrogen atom, and where, the resulting cyclobutane iminium is reduced in a diastereoselective manner. Competition reactions have been performed to fully understand the features of this sequence. Moreover, DFT calculations have verified that the [2+2] cycloaddition step is driven by kinetic and not thermodynamic factors confirming all the experimental observations.     

Development of the [3 + 2] annulations of cyclohexenylsilanes and chlorosulfonyl isocyanate: application to the total synthesis of (+/-)-peduncularine

The synthesis of (+/-)-peduncularine was accomplished using the [3 + 2] annulation of an allylic silane with chlorosulfonyl isocyanate to assemble the bicyclic core of the alkaloid. The stereochemistry of the annulation product was employed to control the installation of the indolylmethyl side chain at C-7 with complete stereoselectivity.     

[2+2] Cycloadditions of Methylene exo-Glycals: Synthesis of Glycopyranosylidene-Spiro-Azetidine-2-ones (β-Lactams) and Cyclobutanones

[2+2] Cycloadditions of methylene exo-glycal derivatives with chlorosulfonyl isocyanate and dichloroketene were studied in detail, investigating the effect of the carbohydrate moiety, protecting groups as well as reaction temperature on the yields of the transformations. These reactions gave new anomeric spiro-β-lactam and spiro-cyclobutanone derivatives, whose structure was established by 1D and 2D NMR and MS experiments. The transformation of spiro-cyclobutanone into spiro-γ-lactone was also demonstrated.     

The stereochemistry of dichloroketene and chlorosulfonyl isocyanate cyclo-addition to 4-t-butylmethylenecyclohexane

The stereochemistry of the cycloaddition of dichloroketene (1) and chlorosulfonyl isocyanate (2) to 4-t-butylmethylenecyclohexane (4) has been investigated as a model for the 2π_s + 2π_a cycloaddition to the methylenecyclohexane system. The reactions are kinetically controlled and proceed mainly by axial attack to yield the thermodynamically less stable isomers 7 and 10, as major products, respectively.     

Rhodium‐Catalyzed Intramolecular [5+2] Cycloaddition of Inverted 3‐Acyloxy‐1,4‐enyne and Alkyne: Experimental and Theoretical Studies

By switching the position of the alkene and alkyne, a new type of 3‐acyloxy‐1,4‐enyne (ACE) five‐carbon building block was developed for Rh‐catalyzed intramolecular [5+2] cycloaddition. An electron‐withdrawing acyl group on the alkyne termini of the ACE was essential for a regioselective 1,2‐acyloxy migration. This new method provided bicyclic [5.3.0]decatrienes that are different from previous methods because of the positions of the alkenes and the acyloxy group. Multiple mechanistic pathways become possible for this new [5+2] cycloaddition and they are investigated by computational studies.     

Study on the reactivity of oxabicyclic alkenes in ruthenium-catalyzed [2+2] cycloadditions

The ruthenium-catalyzed [2+2] cycloadditions of various bicyclic alkenes with an alkyne have been investigated. The presence of the oxygen in the bridgehead of the bicyclic alkene significantly enhanced the rate of the ruthenium-catalyzed [2+2] cycloadditions. The presence of a C1-substituent on the oxanorbornadiene decreased the rate of the cycloaddition and electron-withdrawing C1-substituents were found to be more reactive than electron-donating C1-substituents in the Ru-catalyzed [2+2] cycloaddition. The nature of the substituent on the benzene ring of oxabenzonorbornadienes showed little effect on the rate of the cycloaddition.     

Enantiospecitic Synthesis of 1N-Sulfa-3-Nitro-4-(l,2-Acetonide)-2-Azetidmones

β-lactams are not only to be excellent antibiotics used widely in clinic treatment of many bacteria infected disease but also express some other potential physiology activities, such as antifungal, enzyme inhibition, antineoplastic agent,hypocholesterolemic agent¹⁾. In fact,there are much more methods in the synthesis of derivatives β-lactam²⁾. In the course of our synthetic studies towards a series novel β-lactam analogs we have required a variety of higher optic purity key intermediates. Hear we would like to report the quite easy and versatile way by the cycloaddition of chiral alkene and chlorosulfonyl isocyanate (CSI) to produce those importent mono-ring compounds³⁾.     

Rhodium-catalyzed [2 + 2 + 2] cycloaddition of alkenyl isocyanates and alkynes

A rhodium(I)-catalyzed [2 + 2 + 2] cycloaddition between alkenyl isocyanates and alkynes has been developed. Heating a mixture of an alkenyl isocyanate and a symmetrical internal alkyne in the presence of [Rh(ethylene)2Cl]2/P(4-OMe-C6H4)3 in toluene delivers substituted indolizinones and quinolizinones. Depending on the substrates, a rare fragmentation of the isocyanate unit can be involved within the cycloaddition process to furnish a vinylogous amide embedded in the indolizinone.