1,3-dipolar cycloadditions of aldehydes or imines with ... 1 1,3-dipolar cycloadditions of aldehydes

Download 1,3-dipolar cycloadditions of aldehydes or Imines with ... 1 1,3-Dipolar cycloadditions of aldehydes

Post on 30-Jul-2020

0 views

Category:

Documents

0 download

Embed Size (px)

TRANSCRIPT

  • 1,3-dipolar cycloadditions of aldehydes or Imines with

    carbonyl ylides generated from epoxides: Classical

    heating and microwave irradiation

    Ghenia Bentabed-Ababsa, Mustapha Rahmouni, Florence Mongin, Aicha

    Derdour, Jack. Hamelin, Jean-Pierre. Bazureau

    To cite this version:

    Ghenia Bentabed-Ababsa, Mustapha Rahmouni, Florence Mongin, Aicha Derdour, Jack. Hamelin, et al.. 1,3-dipolar cycloadditions of aldehydes or Imines with carbonyl ylides generated from epoxides: Classical heating and microwave irradiation. Synthetic Communications, Taylor & Francis: STM, Behavioural Science and Public Health Titles, 2007, 37 (17), pp.2935-2948. .

    HAL Id: hal-00781884

    https://hal.archives-ouvertes.fr/hal-00781884

    Submitted on 28 Jan 2013

    https://hal.archives-ouvertes.fr https://hal.archives-ouvertes.fr/hal-00781884

  • HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.

    L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

  • 1

    1,3-Dipolar cycloadditions of aldehydes or imines with carbonyl ylides

    generated from epoxides: classical heating and microwave irradiation

    Ghenia Bentabed

    Synthèse & ElectroSynthèse Organiques, UMR 6510, CNRS-Université de Rennes 1, Bâtiment

    10A, Campus de Beaulieu, Avenue du Général Leclerc, 35042 Rennes Cedex, France

    Mustapha Rahmouni

    Laboratoire de Catalyse et de Synthèse Organique, Université Ibn Khaldoun,

    Tiaret, Algérie

    Florence Mongin

    Synthèse & ElectroSynthèse Organiques, UMR 6510, CNRS-Université de Rennes 1, Bâtiment

    10A, Campus de Beaulieu, Avenue du Général Leclerc, 35042 Rennes Cedex, France

    Aicha Derdour

    Laboratoire de Synthèse Organique Appliquée, Faculté des Sciences de l'Université,

    BP 1524 Es-Senia, Oran 31000, Algérie

    Jack Hamelin and Jean Pierre Bazureau*

    Sciences Chimiques de Rennes, UMR 6226, CNRS-Université de Rennes 1, Bâtiment 10A,

    Campus de Beaulieu, Avenue du Général Leclerc, 35042 Rennes Cedex, France

    Abstract—Cycloadditions of aldehydes with carbonyl ylides to give

    dioxolanes have been carried out without solvent under microwave

    irradiation. The reactions proceeded in similar yields and

    stereoselectivities, but in shorter reaction times, than those obtained

    in toluene at reflux using an oil bath. Cycloadditions conducted

    between imines and carbonyl ylides using the same protocol were less

    efficient since the oxazolidines formed proved unstable under the

    reaction conditions.

    Keywords: 1,3-dipolar cycloaddition, microwave irradiation,

    dioxolanes, oxazolidines.

    * Corresponding author.

    e-mail: jean-pierre.bazureau@univ-rennes1.fr

  • 2

    1. Introduction

    1,3-Dipolar cycloaddition reaction offers a versatile route for building five-membered

    heterocycles. 1 Among dipoles, carbonyl ylides generated from thermal electrocyclic ring

    opening of epoxides are known to undergo [3+2] cycloaddition with -bonds to afford oxa-

    cyclic systems. 2

    A rising number of articles have advocated the use of microwave technology in organic

    synthesis. Harsh conditions such as high temperatures and long reaction times often required

    for cycloaddition reactions could generally be reduced using this technique. 3 In 2003 we have

    published the first microwave-induced syntheses of tetrahydrofurans using 1,3-dipolar

    cycloaddition reactions of alkenes with carbonyl ylides generated from epoxides. 4 In

    continuation of our investigation, we studied the syntheses of dioxolanes and oxazolidines

    using reactions of aldehydes and imines, respectively, instead of alkenes with the same 1,3-

    dipoles. We report here our results on the preparation of 2,4-disubstituted 1,3-dioxolane-5,5-

    dicarbonitriles and 2,3,4-trisubstituted 1,3-oxazolidine-5,5-dicarbonitriles under microwaves.

    2. Results and discussion

    The cycloaddition reactions between a series of aldehydes and carbonyl ylides generated in

    situ from the oxiranes 1 (X = H, Cl, OMe) were first attempted using different reaction

    conditions and methodologies. The best results were obtained using a solvent-free reaction

    coupled with microwave irradiation, 5 with reduction of reaction times in comparison to

    classical heating conditions. 2d,e

    Several experiments were performed, at various powers and irradiation times, in order to find

    the most adequate conditions, which are presented in Table 1. Thus, the dioxolanes 2-3 have

    been prepared by irradiating the mixtures of aldehyde (3,4,5-trimethoxybenzaldehyde or

    piperonal) and epoxide for 30-45 min so as to keep the temperature of the reaction mixture at

    80-120°C.

    The reactions did not proceed when the reactants were heated without solvent in an oil bath,

    because of the more rapid decomposition of epoxides. The use of toluene at reflux afforded

    the dioxolanes 2-3 in similar yields, but after 35 to 72 h of stirring, depending on the electron-

  • 3

    donating ability of the group present at the para-position on the phenyl ring of the epoxide.

    Indeed, it has been previously observed that the reactivity of the epoxide varies in the order 1-

    OMe >> 1-H  1-Cl. 2d,e

    The diastereoisomeric ratios in the mixtures were determined from 1 H NMR spectral analysis,

    and the cis- and trans-products were identified on the basis of their 1 H and

    13 C NMR spectra,

    and in comparison with the literature data. 2d,e

    The ratios proved to be similar using classical

    heating and microwave irradiation, with the cis isomer being the major product.

    Table 1. Reactions between benzaldehydes and epoxides to give 1,3-dioxolanes

    ArCHO + O

    CN

    CN

    X

    1

    conditions

    O

    O

    CN

    CN

    Ar

    X

    +

    O

    O

    CN

    CN

    Ar

    X a b

    Entry ArCHO Epoxide Conditions

    a Products, a:b ratio

    b Main product, yield

    1 OMe OMe

    OMe O

    H

    1-H ● MW, 60 W, rt to 120°C

    then 45 min at 120°C

    2-H, 68/32 2a-H, 49%

    ● toluene, reflux, 35 h 2-H, 77/23 2a-H, 40%

    2 OMe OMe

    OMe O

    H

    1-Cl ● MW, 60 W, rt to 120°C

    then 40 min at 120°C

    2-Cl, 71/29 2a-Cl, 45%

    ● toluene, reflux, 68 h 2-Cl, 72/28 2a-Cl, 42%

    3 OMe OMe

    OMe O

    H

    1-OMe ● MW, 60 W, rt to 80°C

    then 35 min at 80°C

    2-OMe, 70/30 2a-OMe, 55%

    ● toluene, reflux, 45 h 2-OMe, 68/32 2a-OMe, 52%

    4

    O

    H

    O O

    1-H ● MW, 60 W, rt to 120°C

    then 40 min at 120°C

    3-H, 66/34 3a-H, 25%

    ● toluene, reflux, 45 h 3-H, 58/42 3a-H, 31%

    5

    O

    H

    O O

    1-Cl ● MW, 60 W, rt to 120°C

    then 40 min at 120°C

    3-Cl, 60/40 3a-Cl, 39%

    ● toluene, reflux, 72 h 3-Cl, 60/40 3a-Cl, 28%

    6

    O

    H

    O O

    1-OMe ● MW, 60 W, rt to 80°C

    then 30 min at 80°C

    3-OMe, 67/33 3a-OMe, 40%

    ● toluene, reflux, 48 h 3-OMe, 71/29 3a-OMe, 54%

    a For more detailed conditions, see the experimental part.

    b Determined from the

    1 H NMR spectra of the crude mixture.

  • 4

    We next turned our attention to reactions between a series of imines and the oxiranes 1 (X =

    H, Cl, OMe, NO2), and attempted both methods.

    Using classical heating at toluene reflux, the oxazolidines 4-7 were isolated in medium to

    high yields, except with quite unreactive epoxide 1-NO2. The reactivity of the epoxide again

    depends on the electron-donating ability of X, and varies in the order 1-OMe >> 1-H  1-Cl

    >> 1-NO2. 2b,f

    (Table 2).

    Table 2. Reactions between imines and epoxides to give 1,3-oxazolidines

    ArCH=NR + O

    CN

    CN

    X

    1

    toluene reflux

    reaction time

    N

    O

    CN

    CN

    Ar

    X 4-7

    R

    Entry ArCH=NR Epoxide Reaction time Product, yield

    1 CH=NMe

    1-H 24 h 4a, 52%

    2 1-Cl 20 h 4b, 60%

    3 1-OMe 5 h 4c, 78%

    4 1-NO2 35 h 4d, 40%

    5 O

    O

    CH=NPr

    1-H 27 h 5a, 48%

    6 1-Cl 25 h 5b, 59%

    7 1-OMe 9 h 5c, 60%

    8 1-NO2 45 h 5d, 35%

    9 O

    O

    CH=NBu

    1-H 32 h 6a, 56%

    10 1-Cl 32 h 6b, 59%

    11 1-OMe 9 h 6c, 60%

    12 1-NO2 65 h 6d, 18%

    13 O

    O

    CH=NBn

    1-H 40 h 7a, 60%

    14 1-Cl 37 h 7b, 50%

    15 1-OMe 18 h 7c, 80%

    16 1-NO2 72 h 7d, 27%

    As previously reported with benzylidene anilines as imines, 2b,f

    the 1 H NMR spectral analys

Recommended

View more >