Diastereoselectivity of Chiral Nitrone 1,3-Dipolar Cycloaddition to <Emphasis Type="Italic">Baylis-Hillman</Emphasis> Adducts

Summary. 1,3-Dipolar cycloadditions of chiral nitrones to Baylis-Hillman adducts (-hydroxy--methylene esters) proceed with complete regioselectivity in good yields to afford the corresponding diastereomeric 3,5,5-trisubstituted isoxazolidines. Attack of the dipole from the less sterically hindered side of the dipolarophiles affords C-3/C-5 cis isoxazolidines as the predominant isomers. The strong preference for the C-3/C-5 cis isoxazolidines provided more sterically demanding O-tert-butyldimethylsilylsubstituted nitrone 2. Addition of Lewis acids accelerates the reaction and increases the portion of C-3/C-5 trans isoxazolidines. Microwave irradiation accelerates the reaction, but it produces only a small effect on the diastereoisomeric product ratio.     

微波促进的葡萄糖烯与硝酮的1,3-偶极环加成反应

在微波辐射下, 葡萄糖烯(1)与硝酮2环加成反应的效率大大提到, 在乙二醇二甲醚溶液中, 200 ℃封管反应2 min, 环加成反应产物的收率可高达96%, 而且反应的立体选择性无明显变化. 利用环加成产物可进一步合成各种含官能团的碳糖苷衍生物, 找到了一种合成碳糖苷衍生物中间体的简便有效方法.     

Asymmetric 1,3-Dipolar Cycloaddition of the Chiral Nitronic Esters with Acrylate

Sincetheimportantcontributonto1,3-dipolarcycloadditionreactionsbyHuisgeninthe1960s,[1]1,3-dipoleshavebeenwidelyusedinorganicSynthesis.[2,3]oneoftoday'schallengesinthesfieldistocontroltheregio-,diotreo-andenantioselectivitiesofthesereactions,whichhasledtonumerousinvestigationsonthissubjectbytheapplicationofopticallyachvestartingmaterials.[4]Likenitrone,azideandnitrileoalde,nitronicestercanalsoundergol,3-dipolarcycloadditionwithalkenes,I"'1whichhoweverisgreatlylimitedbytheeXtremeinstabilopofthi…     

Diastereoselectivity in the Reaction of N-Glycosyl-nitrones: 1,3-Dipolar Cycloaddition and Addition of Phosphite Anion

The direction of approach of dibenzyl phosphite on the one hand and of dipolarophiles on the other hand to the spironitrone 7 was examined. The nitrone 7 was prepared from the lactone 3 . The nucleophilic addition of dibenzyl phosphite gave 8 as a single adduct (86%). Its structure was established by X-ray analysis. From the cycloaddition of methyl methacrylate, the products 9a, 9b, 11a , and 11b (83:2:7.5:7.5, 81%) were isolated. The structure of the main adduct 9a was established by an X-ray analysis of a derivative of it, and the structures of the other adducts were deduced from their NMR spectra. The cycloaddition of 7 and methyl acrylate gave the adducts 10a , 10b , 12a , 13a , 13b , and 14a (27:10:54:1:2:6, 87%). The structures of these compounds were deduced from their NMR spectra. The results are discussed in relation to prior hypothesis.     

分子内1,3-偶极环加成反应的研究

近几年来,人们对于1,3-偶极环加成反应的理论研究及其在合成上的应用已给予广泛的兴趣和重视。我们曾详细地研究了4-取代苯基(N-4-戊烯基)硝酮的热化学反应性能和其区域选择性以及呋哺偶极体系的热和光化学反应。本文进一步探讨了取代基效应对环加成反应的影响,利用色谱法定量地研究了取代基的电子效应与区域选择性间的关系,并对肉桂醛肟的构型及有关的反应作了研究。     

Intramolecular 1,3-Dipolar Cycloaddition Reactions

The intramolecular 1,3-dipolar cycloaddition reaction of suitably functionalized 1,3-dipoles represents a general scheme for the synthesis of novel fused ring heterocycles. Such reactions of a number of 1,3-dipoles are summarized and the general outline and potential analogies for these reactions noted. While the immediate aim of this review is to survey and correlate published work, it is hoped that general and specific points in need of study will be revealed and will stimulate further work in this fertile field.     

Regioselective Synthesis of Substituted Triazolium Salts via 1,3-Dipolar Cycloaddition Reactions

The regioselectivity of 1,3-dipolar cycloaddition reactions of 1-aza-2-azoniaallene salts with ,-unsaturated nitriles such as acrylonitrile or cyclohexylidene acetonitrile afforded only 1,2,4-triazolium salts via addition to the nitrile group, while the other expected pyrazolium salts were not observed. Moreover, 1-aza-2-azonia-allene salts reacted with other competitive systems such as -iminonitrile derivatives yielding only triazolium salts via addition to the nitrile and not to the imino group. Treatment of cumulene with 3-pyridylnitrile afforded the pyridinium salt. However, 2,3-dimethyl-5-(2,6-dimethoxyphenyl)-[1,2,4]triazole could be prepared from cumulene and 2,6-dimethoxybenzonitrile. Some reactions of nitriles with 1-aza-2-azonia-allene salts prepared from 1,2,3-indantrione and 9-acetylphenanthrene are discussed.     

1,3-偶极环加成反应修饰卟啉化合物

利用1,3-偶极环加成反应对卟啉大环进行修饰是近年来卟啉研究的一个新热点。环加成产物因在可见光谱长波段范围的特征吸收,在构筑人工光反应体系和用作光动力疗法中的光敏剂等领域有重要应用价值。本文综述了1,3-偶极环加成反应在修饰卟啉化合物方面的研究进展,包括：卟啉作为亲偶极体能与甲亚胺叶立德、硝酮、重氮烷、羰基叶立德、腈氧化物等1,3-偶极子反应生成各种新型杂环稠合卟吩类化合物;卟啉化合物作为1,3-偶极子能与C₆₀等亲偶极体反应,生成β位取代的各种新型卟啉化合物;以及扩展卟啉也可以作为亲偶极体与甲亚胺偶极子发生1,3-偶极环加成反应等。     

1,3-偶极环加成合成双-噻唑啉酮衍生物

喹喔啉甲醛;三唑醛;双席夫碱;偶极环加成;双-噻唑啉酮衍生物     

First Example of 1,3-Dipolar Cycloaddition of Carbonyl Ylides to Cyclopropenes

Carbonyl ylide generated from 1-diazo-5-phenylpentane-2,5-dione in the presence of Rh₂(OAc)₄ reacts with 3-substituted cyclopropenes following the 1,3-dipolar cycloaddition pattern to afford substituted 9-oxatricyclo[3.3.1.0^2,4]nonan-6-ones.     

1,3-Dipolar Cycloaddition Reactions of C-(2-Nitro)-styryl-N-phenyl Nitrone Leading to the Regiospecific and Stereospecific Synthesis of New Isoxazolidine Derivatives

New substituted isoxazolidine derivatives have been synthesized through regiospecific and stereospecific 1,3-dipolar cycloadditions of C-(2-nitro)-styryl-N-phenyl nitrone with reactive dipolarophiles in excellent yields and effects of substituents have been noted.     

A Novel Nitrone Cycloaddition/Rearrangement

Adamantanone-derived nitrone 4 and some other keto-nitrones, when reacted with aromatic and aliphatic aldehydes in refluxing toluene or tetrahydrofuran, formed the corresponding aldonitrones (Z)- 10 , the latter arising from the fragmentation of an initially formed 1 , 4 , 2 -dioxazolidine 6 to adamantan-2-one and an oxaziridine intermediate 11 , which then rearranges to (Z)- 10 .     

Some Aspects of the Azide-Alkyne 1,3-Dipolar Cycloaddition Reaction

Russian Journal of Organic Chemistry - Some peculiar features of two most commonly used catalytic systems (Cul and CuSOVsodium ascorbate) controlling the regioselectivity of 1,3-dipolar...     

1,3-偶极环加成法合成异噁唑啉新化合物及其生物活性的研究

以N-甲羟胺硫酸盐和芳香族羰基化合物为主要原料合成了一系列不同的1,3-偶极化合物, 并合成了四种不同的单取代苯乙烯. 以该系列1,3-偶极化合物和单取代苯乙烯为主要中间体, 采用1,3-偶极环加成反应合成了一系列异噁唑啉类新化合物. 同时研究了1,3-偶极化合物与单取代烯发生的1,3-偶极环加成反应, 该合成过程为理想的绿色反应, 合成产物是5位取代异噁唑啉. 通过质谱和核磁共振等表征了化合物的化学结构. 同时对系列异噁唑啉类新化合物进行了实验室内植物生物活性的测试, 发现了对植物灰霉病有效的新化合物.     

手性Lewis酸催化硝酮与烯烃的1,3-偶极环加成反应

综述了近年来利用手性Lewis酸催化剂对映选择催化硝酮与1,2-二取代烯烃的1,3-偶极环加成反应的研究进展.     

Theoretical Study of 1,3-Dipolar Cycloaddition of Hydrazoic Acid to Substituted Ynamines

The 1,3-dipolar cycloaddition reactions of various substituted ynamines with hydrazoic acid were theoretically investigated with the high-accuracy CBS-QB3 method. Two regioisomers, 4-amine, and 5-amine substituted adducts, were obtained, with the former as the preferred yield. This regioselectivity is rationalized by the frontier molecular orbital theory. The reactivity and synchronicity are enhanced with the increase of the electron-withdrawing character of the substitute on ynamine fragment. The calculations also show that the effect of solvent increases the activation energy, and the reaction becomes even harder in polar solvent.     

Soluble Polymer-Supported Synthesis of Pyrazoles via 1,3-Dipolar Cycloaddition Strategy

Rapid parallel liquid-phase synthesis of pyrazoles has first been developed. The 1,3-dipolar cycloaddition between nitrilimines generated in situ and soluble polymer-supported alkynyl or alkenyl dipolarophiles in parallel one-pot fashion gave the corresponding PEG-supported regioisomeric pyrazoles or regiospecific pyrazolines. The latter was assuredly oxidated by DDQ to PEG-supported regiospecific pyrazoles. Cleavage from the support under mild conditions afforded pyrazoles in good yields and high ouritv.