Substitution And Rearrangement Reactions Of Allylic Compounds

DeWolfe, Robert H.; Young, W. Glenn

doi:10.1021/cr50010a002

Cited by 247 publications

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“…It should be noted that we observed no further transformations of 3-(2-propynyloxy)propan-2-ols IIa and IIb, such as prototropic rearrangements in the 2-propynyl or allyl (in IIa) fragments (e.g., acetyleneallene [12,23] and/or allyl-propenyl isomerization [24][25][26]) or intramolecular cyclizations involving hydroxy group and triple bond [2][3][4][5][6][7][8]12], which are usually promoted by bases. A probable reason is the low concentration of the catalyst (~0.05 mol per mole of oxirane).…”

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confidence: 70%

Vinyl Ethers Containing an Epoxy Group: XXII. Synthesis and Base-Catalyzed Transformations of 1-(Allyloxy)- and 1-[2-(Vinyloxy)ethoxy]-3-(2-propynyloxy)propan-2-ols

et al. 2005

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Reactions of 2-(allyloxymethyl)-and 2-[2-(vinyloxy)ethoxy]methyloxiranes with 2-propynol (~3 wt % of t-BuOK, 75-85°C, 5-10 h) lead to formation of new 1-organyloxy-3-(2-propynyloxy)propan-2-ols (yield 65-95%). On heating to 45-100°C in the presence of bases (KOH, t-BuOK), 1-allyloxy-and 1-[2-(vinyloxy)ethoxy]-3-(2-propynyloxy)propan-2-ols are transformed into the corresponding 2-vinyl-1,3-dioxolane, 6-methyl-2,3-dihydro-1,4-dioxine, 6-methylene-1,4-dioxane, and 2,3-dihydro-5H-1,4-dioxepine derivatives, whose yield and ratio strongly depend on the solvent nature, catalyst, and substituent at the hydroxy group. 2-Vinyl-1,3-dioxolane and 6-methyl-2,3-dihydro-1,4-dioxine derivatives are formed as the major products (yield 70-99%) in the presence of t-BuOK in aprotic media (toluene, THF, DMSO) or in the absence of a solvent as a result of prototropic isomerization followed by intramolecular heterocyclization. Intramolecular nucleophilic cyclization of 3-(2-propynyloxy)propan-2-ols to 6-methylene-1,4-dioxane is the predominant process in water in the presence of KOH. In all cases, the fraction of 2,3-dihydro-5H-1,4-dioxepine derivatives among the cyclization products ranges from 0 to 5% (KOH) or to 14% (t-BuOK). * For communication XXI, see [1]. Base-catalyzed intramolecular cyclizations of -(2-propynyloxy)-[2-8], -(2-propynylsulfanyl)-[9], and -(2-propynylamino)alkan-1-ols [10,11], as well as of their 2-haloallyl analogs [4,5,9], have been studied in sufficient detail. Such cyclizations (which involve intramolecular nucleophilic addition of functional group at the acetylenic triple bond) are among the most widespread reactions leading to five-, six-, or seven-membered heterocycles containing one or two heteroatoms (N, O, S) [8,12, 13]. However, in the series of -(2-propynyloxy)alkan-1-ols, only 2-(2-propynyloxy)ethanol and its simplest derivatives R 1 C CC(R 2 )(R 3 )OCH(R 4 )CH(R 5 )OH (R 1 = R 2 = R 3 = R 4 = R 5 = H [3, 4, 7]; R 1 = R 2 = R 3 = R 4 = H, R 5 = Me, Ph; R 1 = R 2 = R 3 = R 5 = H, R 4 = Ph; R 1 = R 2 = R 3 = H, R 4 = R 5 = Me [3, 6]; R 1 = R 2 = R 4 = R 5 = H, R 3 = Me [7]; R 1 = R 4 = R 5 = H, R 2 = Me, R 3 = Ph [8]; R 1 = R 2 = R 4 = H, R 3 = R 5 = Me [3, 6, 7]; R 1 = Me, R 2 = R 3 = R 4 = R 5 = H [7]), 3-(2-propynyloxy)propan-1-ol [5], 2-(2-propynyloxy)cyclopentanol [7], and 2-(2-propynyloxy)cyclohexanol [3, 6, 7] were studied.Obviously, introduction of additional reaction centers, e.g., olefinic fragments with qualitatively different chemical natures of the double carbon-carbon bonds (specifically vinyloxy and allyloxy groups), into (2-propynyloxy)alkanol molecules should strongly extend the synthetic potential of both initial alkanols [1][2][3][4][5][6][7][8]12] and their cyclization products [1,8,14], as well as the range of their useful properties and the scope of practical application. Known representatives of this class of compounds are used in various fields (see, e.g., references in [1]), including the synthesis of dendrimers, dienes, -hydroxy and -oxo acids, -hydroxymethyl ketones, , '-dihy...

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confidence: 70%

Vinyl Ethers Containing an Epoxy Group: XXII. Synthesis and Base-Catalyzed Transformations of 1-(Allyloxy)- and 1-[2-(Vinyloxy)ethoxy]-3-(2-propynyloxy)propan-2-ols

et al. 2005

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“…That this holds not only for 7 h in which X is methylg), but also for the a-chloroallylboronates is seen from the data on the reactions of 15a -c in Table 1. 16 Polar Effects: It is obvious from Table 1 that the underlying small preference for the formation of the Z-isomer 14 caused by steric effects is enhanced when the substituent X in the allylboronate becomes more and more electronegative. In view of the dipole moment of the boron-oxygen bond it seems plausible that such conformations are more stable in which the C -X dipole opposes at least one of the B -0 dipoles or better their vectorial sum.…”

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confidence: 99%

Stereoselective synthesis of alcohols, XXII. E/Z‐selectivity on addition of α‐substituted allylboronates to aldehydes

Hoffmann

Landmann

1986

Chem. Ber.

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a-Heterosubstituted allylboronates 7 are prepared. Addition of 7 to aldehydes results in E/Z-isomeric hornoallyl alcohols 13 and 14: The reasons for the predominant formation of the Z-isomer 14 are discussed. The Z-bromo olefins 16 and 20 obtained in this way serve as starting point for chain extension or formation of &lactones 21. Many allyl metal compounds add to aldehydes and ketones with "allyl inversion" *). Those allyl metal compounds having a n a-alkyl branch should therefore lead to adducts 1 with a linear alkene chain. Accordingly, this reaction ought to be useful for assembling larger alkyl chains". The same target could be reached by using a-heterosubstituted allyl metal compounds, which can be considered as multicoupling building blocks 34), because in the resulting adducts 2 the heteroatom can be substituted by an alkyl chain using either the cuprate-') or the NiO-@ and Pdo7)-catalyzed carbon carbon bond forming reactions. Stereoselektive Synthese von -Met 4-y"Of course, such methodology requires that structurally defined q '-ally1 metal compounds are existant and available. Yet these compounds appear to be exceptional in view of the generally fluctional nature of the allyl compounds of electropositive metals.

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“…It was estimated that the error in the 2-ol:1-ol ratios were approximately Ϯ 5%. In H 2 O, the 2-ol:1-ol ratio has been reported as 5.7 (DeWolfe and Young, 1956). Figure 4 shows that the 2-ol:1-ol ratios are greatest in the PPG 425 solutions with values ranging from 4.1 to about 4.8 indicating little dependence of selectivity on water content.…”

Section: Resultsmentioning

confidence: 99%

Effect of aqueous PEG or PPG solvents on reaction selectivity and Gibbs energies

2004

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Substitution And Rearrangement Reactions Of Allylic Compounds

Cited by 247 publications

References 0 publications

Vinyl Ethers Containing an Epoxy Group: XXII. Synthesis and Base-Catalyzed Transformations of 1-(Allyloxy)- and 1-[2-(Vinyloxy)ethoxy]-3-(2-propynyloxy)propan-2-ols

Vinyl Ethers Containing an Epoxy Group: XXII. Synthesis and Base-Catalyzed Transformations of 1-(Allyloxy)- and 1-[2-(Vinyloxy)ethoxy]-3-(2-propynyloxy)propan-2-ols

Stereoselective synthesis of alcohols, XXII. E/Z‐selectivity on addition of α‐substituted allylboronates to aldehydes

Effect of aqueous PEG or PPG solvents on reaction selectivity and Gibbs energies

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