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Synlett 2004(9): 1577-1578  
DOI: 10.1055/s-2004-829537
LETTER
© Georg Thieme Verlag Stuttgart · New York

Reaction of Bromo Dipoles with (Z)-4-(Arylmethylene)azol-5-ones. Substrate-Controlled Synthesis of New Bromo-Substituted Heterocyclic Spirans and Unusual N-Benzoyl α-Aminoacids

Francesco Foti*a, Giovanni Grassia, Francesco Risitanoa, Enrico Rotondob, Domenico Zonaa
a Dipartimento di Chimica Organica e Biologica, Università, Vill. S. Agata, 98166 Messina, Italy
Fax: +39(090)393897; e-Mail: ffoti@isengard.unime.it;
b Dipartimento di Chimica Inorganica, Analitica e struttura Molecolare, Università, Vill. S. Agata, 98166 Messina, Italy
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Publication History

Received 6 April 2004
Publication Date:
29 June 2004 (online)

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Abstract

Bromo spirans 6 and 7 and unusual α-aminoacids 8 were prepared as diastereoisomerically pure compounds from bromo ­dipoles and (Z)-4-arylmethyleneazolones.

Key words

dipolar cycloadditions - nitrile oxides - nitrile imines - bromoheterocycles

    References

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  • 8b

    1H NMR, 13C NMR, and 15N NMR spectra were recorded with a Bruker ARX 300 spectrometer at 300.13, 75.47, and 30.41 MHz, respectively. The 1H NMR spectra were calibrated against the residual proton signal of the solvent (CDCl3: δ = 7.24 ppm), the 13C{1H} NMR spectra against the triplet of the solvent (CDCl3: δ = 77.0 ppm), and the 15N{1H} NMR spectra against external CH3NO2 (1v:1v) in CDCl3 at δ = 379.60 ppm.

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  • 9b

    Selected data for 9: mp 210-211 °C. IR (nujol): 3398, 3243, 3166, 1734, 1698 cm-1. 1H NMR (300 MHz, DMSO-d 6): δ = 7.47 (s, HC-4), 10.83 (s, 1 H). MS (EI):
    m/z = 309/311 [M+].
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3

Spyrans 6a-c were synthesized from 4-arylmethylene-imidazolones 1 and bromonitrilimine 4 at r.t. by a route analogous to that previously described in ref. [1]

4

Typical procedure for bromonitrile oxide cycloaddition: To a stirred mixture of EtOAc (50 mL) and NaHCO3 (4.2 g, 50.0 mmol) was added a solution of 2 or 3 (10 mmol) and dibromoformaldoxime [11] (2.7 g, 13.0 mmol) in THF at r.t. The reaction was stirred for ca. 24 h at r.t. After completion of the reaction, the mixture was filtered and evaporated in vacuo. EtOAc was then added to the residue. The residue was washed twice with brine, dried over Na2SO4, and the solvent was removed under vacuum. Column chromatography of the residue on silica gel (CHCl3) gave the indicated products as colorless crystals.

7

Selected data. Compound 6a: mp 114-116 °C. IR (nujol): 1758 cm-1. 1H NMR (DMSO-d 6): δ = 5.06 (s, HC-4). 13C NMR (DMSO-d 6): δ = 67.8 (C-4), 92.3 (C-5). MS (EI):
m/z = 444/446 [M+]. Compound 6b: mp 119-121 °C. IR (nujol): 1755 cm-1. 1H NMR (DMSO-d 6): δ = 5.05 (s, HC-4). 13C NMR (DMSO-d 6): δ = 67.3 (C-4), 92.4 (C-5). MS (EI): m/z = 458/460 [M+]. Compound 7a: mp 190-191 °C. IR (nujol): 1801, 1747 cm-1. 1H NMR (DMSO-d 6): δ = 5.10 (s, HC-4). 13C NMR (DMSO-d 6): δ = 59.2 (C-4), 96.1 (C-5). MS (EI): m/z = 309/311 [M+]. Compound 7b: mp 240-242 °C. IR (nujol): 3336, 1796, 1752 cm-1. 1H NMR (DMSO-d 6): δ = 5.01 (s, HC-4). 13C NMR (DMSO-d 6):
δ = 59.0 (C-4), 95.7 (C-5). MS (EI): m/z 340/342 [M+]. Compound 7c: mp 264-265 °C. IR (nujol): 1746 cm-1. 1H NMR (DMSO-d 6): δ = 5.11 (HC-4). 13C NMR (DMSO-d 6):
δ = 59.1 (C-4), 96.2 (C-5). MS (EI): m/z = 344-346 [M+]. Compound 8a: mp 128-130 °C. IR (nujol): 3485,1709, 1684 cm-1. 1H NMR (DMSO-d 6): δ = 5.55 (s, HC-4). MS (EI): m/z = 338/390 [M+]. Compound 8b: mp 164-165 °C. IR (nujol): 3438, 1713, 1698 cm-1. 1H NMR (DMSO-d 6): δ = 3.61 (s, 3 H), 5.55 (s, HC-4). MS (EI): m/z = 418/420 [M+].

10

X-ray data to be submitted to Acta Cryst.