Synthesis of Mono- and Polycyclic Tricarbonyliron Cyclohexa-2,4-dienone Complexes and Phenols from Tosylhydrazones of Acyclic Dienone Complexes

Abstract

Cyclohexa-2,4-dienones stabilized by coordination to tricarbonyliron are obtained when the tosylhydrazones of tricarbon­yliron-complexed α-dienones are thermolyzed in the presence of strong bases. This cyclocarbonylation reaction of carbenic intermediates is fairly general and can be used to synthesize various mono and polycyclic cyclohexadienone complexes or their decomplexed phenolic tautomers, and among them a new salicylate in the phenanthrene series.

Key words

tricarbonyliron diene complexes - diazo compounds - cyclocarbonylation - cyclohexadienones - salicylates

References

• 1 Franck-Neumann M. Geoffroy P. Winling A. Synlett  1995,  341 
• 4 Cais M. Maoz N. J. Organomet. Chem.  1966,  5:  370 
• 5 Salzer A. Schmalle H. Stauber R. Streiff S. J. Organomet. Chem.  1991,  408:  403 
• Typical Experimental Procedure:
• 7a

  Tosylhydrazone 12: A solution of the complexed β-ionone 11 [2.00 g, 6.0 mmol, from β-ionone (1.90 g) and diironnonacarbonyl (3.50 g)], tosylhydrazine (1.20 g, 6.4 mmol) and p-toluenesulfonic acid (0.15 g, 0.8 mmol) in dimethoxyethane (50 mL) was stirred at room temperature for 24 h. Diethyl ether (75 mL) was added and the solution was washed with saturated aqueous solutions of NaHCO₃ and NaCl, and dried with MgSO₄. The solvents were removed by evaporation (30 °C, 15 Torr) and the residue was purified by chromatography on a silica gel column (90 g, Merck Si60, eluent hexane with 30% CH₂Cl₂). 2.20 g tosylhydrazone 12 (C₂₃H₂₈N₂O₅S Fe, 4.4 mmol, 73%, yellow crystals, mp 170 °C) were obtained.

• 7b

  Cyclocarbonylation : NaH (40 mg, 1.7 mmol) was added to a stirred solution of the tosylhydrazone 12 (600 mg, 1.2 mmol) in mesitylene (50 mL). Cu(acac)₂ (31 mg, 0.12 mmol) was added and the air atmosphere over the mixture was replaced by carbon monoxide (several degassings under reduced pressure). The temperature was gradually raised from room temperature to 110 °C in 30 min and kept at 110 °C for further 20 min. About 80% of the solvent was evaporated (30 °C, 0.1 Torr), and the resulting solution was chromatographed on SiO₂ (60 g, eluent hexane with 0% to 40% diethyl ether). 128 mg cyclohexadienone complex 13a (0.37 mmol, 31%) were obtained.
  Cyclohexadienone complex 13a: yellow crystals, mp 100 °C; Anal. calcd for C₁₇H₂₀O₄Fe: C, 59.29; H, 5.86. Found: C, 59.28; H, 6.08; IR (CCl₄) ν_max 2050, 1990, 1979, 1651 cm^-1; ¹H NMR (200 MHz, C₆D₆) δ 0.64 (s, 3 H), 0.84 (s, 3 H), 0.91 (s, 3 H), 1.11-1.45 (mm, 4 H), 1.52 (s, 3 H), 1.99 (m, 2 H), 4.64 (d, J = 5.0 Hz, 1 H), 4.88 (d, J = 5.0 Hz, 1 H); ¹³C NMR (50 MHz, CDCl₃) δ 17.48, 17.80, 31.48, 35.29, 36.58, 39.56, 43.14, 71.03, 81.75, 83.83, 101.57, 191.68.

• Known hydroxy-9,10-dihydro-phenanthrene-carboxylic acids:
• 8a 2-hydroxy-9,10- dihydrophenanthrene-3-carboxylic acid : Mossetig E. Stuart AH. J. Am. Chem. Soc.  1939,  61:  1 
• 8b 3-hydroxy-2-carboxylic acid and 2-hydroxy-9,10- dihydrophenanthrene-3-carboxylic acid: Chan T.-H. Brownbridge P. J. Am. Chem. Soc.  1980,  102:  3534 
• 9 Pal K. Synthesis  1995,  1485 
• 10 Franck-Neumann M. Geoffroy P. Tetrahedron Lett.  1994,  35:  7027 
• 11 Franck-Neumann M. Martina D. Brion F. Angew. Chem., Int. Ed. Engl.  1978,  17:  690 ; Angew. Chem. 1978, 90, 737
• 13 Hansen MM. Riggs JR. Tetrahedron Lett.  1998,  39:  2705 
• 14a Banerjee AK. Pena-Matheud CA. de Carrasco MC. J. Chem. Soc., Perkin Trans. 1  1988,  2485 
• 14b Dauben WG. Ashcraft AC. J. Am. Chem. Soc.  1963,  85:  3673 
• 15 Khodabocus A. Shing TKM. Sutherland JK. Williams JG. J. Chem. Soc., Chem. Commun.  1989,  783 

2

The phenols are more difficult to observe (TLC) and to isolate than the very polar and essentially non-volatile cyclohexadienone complexes. However, they could be isolated as Boc-protected phenols, when Boc₂O/DMAP was added immediately after thermolysis, these reagents achieving not only protection, [13] but probably also decomplexation.

3

The complex 7 was obtained by complexation [71%, Fe₂(CO)₉, benzene, 60 °C] of the crotonization product of cyclohexene-1-carboxaldehyde-1 with acetone (63%, NaOH/H₂O).

6

The details of the X-ray structure (Figure [1] ) determination will be given in the full paper (Service Communs de Rayons X de l’Institut de Chimie de l’ULP).

Figure 1 Ortep view of 13a (mp 100 °C).

12

The cyclohexadienone 23 has been prepared for the synthesis of herbertene, [14] in 8 steps from 3-keto-10-methyl-Δ⁴-octalin and with an overall yield of 5.3%. Another synthesis in 5 steps from β-ionone was reported, however without any indication of yields. [15]