The Reaction of α,β-Unsaturated Sulfones with Isobenzofuran and N-Boc-isoindole Using Warrener’s Methodology

Abstract

The cycloaddition reaction of vinyl and acetylenic sulfones with isobenzofuran {benzo[c]furan} and N-Boc-isoindole generated in situ using Warrener’s tetrazine method is described for the first time.

Key words

Diels-Alder reactions - sulfones - isobenzofuran - isoindole - Warrener’s reaction.

References and Notes

• For reviews on the reaction, synthesis, and applications of benzofurans including isobenzofurans see:
• 1a Hou XL. Yang Z. Wong HNC. Progress in Heterocyclic Chemistry   Part 3, Vol. 15:  Gribble GW. Joule JA. Pergamon; Oxford: 2003.  Chap. 5. p.192-199  
• 1b Hou XL. Yang Z. Yeung KS. Wong HNC. Progress in Heterocyclic Chemistry   Part 3, Vol. 16:  Gribble GW. Joule JA. Pergamon; Oxford: 2004.  Chap. 5. p.180-188  
• 1c Hou XL. Yang Z. Yeung KS. Wong HNC. Progress in Heterocyclic Chemistry   Part 3, Vol. 17:  Gribble GW. Joule JA. Pergamon; Oxford: 2005.  Chap. 5. p.158-164  
• 1d Hou XL. Yang Z. Yeung KS. Wong HNC. Progress in Heterocyclic Chemistry   Part 3, Vol. 18:  Gribble GW. Joule JA. Pergamon; Oxford: 2006.  Chap. 5. p.203-210  
• 1e Hou XL. Yang Z. Yeung KS. Wong HNC. Progress in Heterocyclic Chemistry   Part 3, Vol. 19:  Gribble GW. Joule JA. Pergamon; Oxford: 2007.  Chap. 5. p.193-200  ; see also previous issues of this series
• 1f For a more extensive review on isobenzofuran, including many synthetic applications, see: Rodrigo R. Tetrahedron  1988,  44:  2093 
• 1g For reviews on the isoindole chemistry, see: Bounett R. North SA. Adv. Heterocycl. Chem.  1981,  29:  341 
• 1h See also: Joule JA. In Rodd’s Chemistry of Carbon Compounds   2nd ed.:  Elsevier; Amsterdam: 1997.  p.557-605  
• For methods of generation of IBF excluding Warrener’s methodology, see ref. 1f and:
• 2a Peters O. Friedrichsen W. Trends Heterocycl. Chem.  1995,  4:  217 
• 2b Hurst DT. In Rodd’s Chemistry of Carbon Compounds   2nd ed.:  Elsevier; Amsterdam: 1997.  p.283-335  
• 2c Friedrichsen W. Adv. Heterocycl. Chem.  1999,  73:  1 
• For others more recent references, see:
• 2d Sambaiah T. Huang DJ. Cheng CW. J. Chem. Soc., Perkin Trans. 1  2000,  195-203  
• 2e Mikami K. Ohmura H. Org. Lett.  2002,  4:  3355 
• 2f

  See also ref. 10.

• Isobenzofurans:
• 3a Warrener RN. J. Am. Chem. Soc.  1971,  93:  2346 
• 3b Russell RA. Longmore RW. Warrener RN. Weersuria KD. Aust. J. Chem.  1991,  44:  1341 
• Isoindoles:
• 3c Watson PL. Warrener RN. Tetrahedron Lett.  1972,  4295 
• 3d Malpass JR. Sun G. Fawcett J. Warrener RL. Tetrahedron Lett.  1998,  39:  3083 
• For the synthesis and isolation of mono- and bisoxadisilole fused isobenzofurans, see:
• 3e Chen YL. Hau ChK. Wang H. He H. Wong MS. Lee AWM. J. Org. Chem.  2006,  71:  3512 
• These reactions coupled with 1,3-dipolar cycloaddition reactions constitute the synthetic strategy for the stereocontrolled construction of [n]polynorbornanes structures. For reviews, see:
• 4a Warrener RN. Butter ON. Russell RA. Synlett  1998,  566 
• 4b Warrener RN. Eur. J. Org. Chem.  2000,  3363 
• For theoretical calculations on these reactions, see:
• 4c Dinadayaladane TC. Tandapani C. Sastry GN. J. Chem. Soc., Perkin Trans. 2  2002,  1902 
• 4d Dinadayaladane TC. Punnagay M. Sastry GN. THEOCHEM  2003,  626:  247 
• 4e Margetic D. Warrener RN. Dibbfe PW. J. Mol. Model.  2004,  10:  87 
• 5 Simpkins NL. In Sulphones in Organic Synthesis   Baldwin JE. Magnus PD. Tetrahedron Organic Chemistry Series, Pergamon Press; Oxford: 1993.  Chap. 6. p.236-245  
• 6 See ref. 5, Chap 9 and: Nájera C. Yus M. Tetrahedron  1999,  55:  10547 
• See, for instance:
• 7a De Lucchi O. Luchini V. Pasquato L. Modena G. J. Org. Chem.  1984,  49:  596 
• 7b De Lucchi O. Modena G. Tetrahedron  1984,  40:  2585 
• 7c De Lucchi O. Licini G. Pasquato L. Senta M. Tetrahedron Lett.  1988,  29:  831 
• 7d Azzena U. Cossu S. De Lucchi O. Melloni G. Tetrahedron Lett.  1989,  30:  1845 
• For selected accounts, see:
• 8a Dittmer DC. Takashina N. Tetrahedron Lett.  1964,  3809 
• 8b Sridhar M. Krishna KL. Sriniras K. Rao JM. Tetrahedron Lett.  1998,  39:  6529 
• For selected accounts, see:
• 9a Glass RS. Smith DL.
  J. Org. Chem.  1974,  39:  3712 
• 9b Hanack M. Massa F. Tetrahedron Lett.  1977,  661 
• 9c Riera A. Martí M. Moyano A. Pericás MA. Santamaría J. Tetrahedron Lett.  1990,  31:  2173 
• 9d Back TG. Parvez M. Zhai H. J. Org. Chem.  2006,  71:  5254 
• Rickborn et al. reported the synthesis of 7e (99% isolated yield, Scheme 3) by reaction of IBF generated from acetal 8 and (E)-1,2-bisphenylsulfonylethylene.^10a On the other hand, Padwa et al. reported the capture of the isobenzofuran 10 generated from sulfoxide 9, with the same dienophilic reagent to give 11 as 1:1 diastereoisomeric mixture (69%).^10b See:
• 10a Mirsadeghi S. Rickborn B. J. Org. Chem.  1985,  50:  4340 
• 10b Padwa A. Cochran JE. Kappe CD. J. Org. Chem.  1996,  61:  3706 
• 11 Synthesized according to: Cho YH. Fayol A. Lautens M. Tetrahedron: Asymmetry  2006,  17:  416 

12

General Procedure
To equimolecular amounts of tetrazine 3, compounds 4 or 5, and sulfone 6, DMSO (10 mL/mmol) was added. The reaction mixture was stirred under Ar at r.t. for 24 h. After this time the reaction mixture was extracted with Et₂O (5 mL) and washed with H₂O (3 × 10 mL). The organic phase was dried over MgSO₄. After removal of the solvent under reduced pressure, the crude product was purified by column chromatography (SiO₂, hexane-EtOAc, 7:3).

13

Compounds 7 were characterized by IR, ¹H NMR, and ¹³C NMR spectra and mass spectral analysis. In the case of compound 7e, spectroscopic data matched with those previously reported. See ref. 10a.

14

Determined by ¹H NMR integration. Key signals: exo adduct: H₂, δ = 3.16 ppm, dd; endo adduct: H₂, δ = 3.96 ppm, dt.

15

Determined by ¹H NMR integration. Key signals: exo adduct: H₂, δ = 3.28 ppm, dd; endo adduct: H₂, δ = 4.00 ppm, dt.