Regioselective Nucleophilic Addition Research Articles

Photoinduced Alkoxylation of 2-Vinylpyridinium Ion

Abstract Photoirradiation of 2-vinylpyridine in acidic methanol afforded methyl 2-(2-pyridyl)ethyl ether in a high yield. Reactions in acidic ethanol and 2-propanol also provided the corresponding alkoxyl derivatives along with a considerable amount of 2-ethylpyridine. It was suggested that photoinduced intramolecular charge-shift from the pyridinium ion moiety into the vinyl group initiates the regioselective nucleophilic addition of alcohol.

有機金属活性種の開発とその合成化学的展開

The reactivity features of photochemically and chemically generated reactive species from organometallic compounds and their applications in organic synthesis are described. The reactive species include exciplexes, radical ions, and radicals involving group 14 organometallic compounds, and also iron complexes generated from Fe3 (CO) 12 and Bu4NFe(CO)3NO. By utilizing the specific chemical properties of these reactive species, a variety of new, highly selective synthetic reactions have been developed. The typical examples of the developed reactions are as follows : 1) synthesis of Si-and Ge-containing spiro and cyclophane compounds, 2) photo-allyl and arylmethylation of aromatic nitriles, 3) photo-allylation and silylation of electron-deficient alkenes, 4) double vicinal C-C bond formation on electron-deficient alkenes, 5) cyclodimerization of α, β-unsaturated carbonyl compounds, 6) pyrrole formation via reductive deoxygenation of dihydro-1, 2-oxazines, 7) regioselective nucleophilic and electrophilic addition to the allylic ligands of (η3-allylic) Fe (CO)2NO complexes, and 8) 1, 4-functionalization of 1, 3-dienes. The methods for enhancing the efficiencies and selectivities of photoreactions involving electron-transfer are also described.

ChemInform Abstract: α,β‐Unsaturated Thio Compounds. Part 22. Regioselective Nucleophilic Addition to 3‐Alkoxy‐ and 3‐Alkylthio‐2‐aryl‐1‐indeniminium Salts as a Way of Synthesis of 1,1,3‐Trisheterofunctional Derivatives of Indene.

AbstractThe hitherto unknown title compounds, the 1,1,3‐trisheterofunctionalized derivatives (III), (V), (VII) and (IX) as well as (XI) and (XII) are prepared by reacting the 3‐alkylthio‐ and 3‐alkoxyindeniminium salts (I) or (VIII) with hard and soft nucleophiles.

Regioselective nucleophilic additions to tricarbonyl(η6-arene)chromium(0) complexes: electronic versus chelation control

Regioselective addition of t-butyl-lithium to tricarbonyl(η6-benzyl alcohol)chromium(0) proceeds to give tricarbonyl(η6-5-methylene-6-exo-t-butylcyclohexa-1,3-diene)chromium(0), which can be isomerised to tricarbonyl(η6-o-t-butyltoluene)chromium(0). Repetition of the reaction on tricarbonyl(η6-1 -phenethanol)chromium(0) gives regio- and stereo-selectively the corresponding 5-ethylidene complex.

Studies of the Factors Controlling Regioselective Nucleophilic Addition to Dienylium‐Iron Complexes

AbstractTricarbonyl(4‐alkoxyl‐1‐alkylcyclohexadienylium)iron complexes (I) react with metal‐cation enolate nucleophiles to give in most cases a mixture of products (II) and (III), resulting from attack at the C‐1 and C‐5 termini of the dienylium ring. Factors that control the regioselectivity of nucleophilic addition, including the steric and electronic effects of the 4‐alkoxyl and 1‐alkyl substituents, the degree of association between the enolate nucleophiles and their counterions, and the polarity of the solvents, were investigated.

Regioselective nucleophilic addition of organolithium compounds to 3-(4,4-dimethyloxazolin-2-yl)pyridine

The nucleophilic heteroaromatic addition reactions of 3-(4,4-dimethyloxazolin-2-yl)pyridine (8) with organolithium compounds as nucleophilic reagents have been investigated. Strongly nucleophilic reagents have been observed to add preferentially to the γ- rather than the α-position of the pyridine ring. Stable crystalline 4-substituted 3-(4,4-dimethyloxazolin-2-yl)-1,4-dihydropyridine addition products have been isolated in good yields. Further, the dihydropyridines could be oxidized to the corresponding 3,4-disubstituted pyridines by a variety of oxidizing agents. Interesting oxidative dealkylations of the 4-t-butyl-1,4-dihydropyridine (9e) have been observed, and they may account for the anomalous ratio of aromatized products.

Synthetic approaches towards 4-ylidenebutenolides and 4-ylidenetetronic acids. Regioselective nucleophilic additions to unsymmetrically substituted maleic anhydrides

The application of unsymmetrically substituted maleic anhydrides in the synthesis of but-2-enolides, 4-hydroxybut-2-enolides, 4-ylidenebut-2-enolides, and 4-ylidenetetronic acid derivatives is examined. Reduction of 2-methylmaleic anhydride with metal hydride agents leads to a mixture of but-2-enolides (8a) and (8b), and 4-hydroxybut-2-enolides (7a) and (7b) corresponding to ca. 88% regioselective hydride ion attack at the more hindered (C-1) carbonyl function in the anhydride. Similar reductions of methoxy-substituted anhydrides (13) and (16) were completely regioselective and led to tetronic acid and 4-hydroxytetronic acid products resulting from hydride ion attack at only C-1 in the anhydrides.Condensation of the phosphorane (22a) with 2-methylmaleic anhydride produced largely the E-ylidenebutenolide (23), accompanied by smaller amounts of the Z-butenolides (24) and (25) : similar condensations with the anhydrides (16a) and (16b) were totally regioselective and produced Z,E-mixtures of ylidenetetronic acids corresponding to attack at C-1 in the anhydrides. The addition of ethylmagnesium bromide to 2-methylmaleic anhydride, followed by dehydration of the intermediate carbinol, led to a 3 : 2 mixture of the ylidenebut-2-enolides (39) and (40), whereas the corresponding reaction with the 2-methoxy-anhydride (16b) was more selective producing only (41).These studies have provided a basis for the development of syntheses of the ‘pulvinone,’‘pulvinic acid,’ and ‘multicolic acid’ groups of natural pigments.

ChemInform Abstract: UNEXPECTED REGIOSELECTIVE NUCLEOPHILIC ADDITION TO 3‐(4,4‐DIMETHYLOXAZOLIN‐2‐YL)PYRIDINE: FORMATION OF STABLE 1,4‐DIHYDROPYRIDINES

Chemischer InformationsdienstVolume 9, Issue 45 Heterocyclic Compounds ChemInform Abstract: UNEXPECTED REGIOSELECTIVE NUCLEOPHILIC ADDITION TO 3-(4,4-DIMETHYLOXAZOLIN-2-YL)PYRIDINE: FORMATION OF STABLE 1,4-DIHYDROPYRIDINES C. S. GIAM, C. S. GIAMSearch for more papers by this authorA. E. HAUCK, A. E. HAUCKSearch for more papers by this author C. S. GIAM, C. S. GIAMSearch for more papers by this authorA. E. HAUCK, A. E. HAUCKSearch for more papers by this author First published: November 7, 1978 https://doi.org/10.1002/chin.197845203Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume9, Issue45November 7, 1978 RelatedInformation

Unexpected regioselective nucleophilic addition to 3-(4,4-dimethyloxazolin-2-yl)-pyridine: formation of stable 1,4-dihydropyridines

The regioselective addition of organolithium reagents to 3-(4,4-dimethyloxazolin-2-yl)pyridine leads to stable 1,4-dihydropyridines.

Regioselective nucleophilic addition to 3,4-lutidine

Regioselective nucleophilic addition to 3,4-lutidine

Regioselective nucleophilic additions to unsymmetrically substituted maleic anhydrides

Regioselective nucleophilic additions to unsymmetrically substituted maleic anhydrides