Synthesis of 1,6‐Disubstituted Cycloheptatriene Derivatives from Benzocyclopropene

Abstract

2): A powerful stream of phosgene was passed into the suspension of ( I ) (46.8 g, 0.4 mol) in tetrahydrofuran (THF) (600 mL) at 40°C until (1) was in solution (ca. 30 min). After 1 hours purging with anhydrous N2 the solvent was removed in uacuo, the residue taken up in a little THF, and the solvent once again removed by distillation in vacuo (removal of hydrogen chloride!). (2) was dried for 30 min at 40°C in uacuo; the yield was quantitative.(5): The solution of (2) (ca. 0.4 mol) in THF (400 ml) was added dropwise to a vigorously stirred mixture of ( 3 . HCI) (55.8 g, 0.4 mol), triethylamine (90.9 g, 0.9 mol) and CHCI3 (500 mL) (2L three-necked flask) at -70 to -60°C. After 3 hours stirring at -70°C and 30 min at room temperature the triethylamine hydrochloride was separated off by suction, the solvent removed from the solution by distillation in uacuo (40 O C bath temperature), and the residue was taken up in 1700 mL toluene. The resulting solution and then suspension was heated for 12 h under reflux with (efficient mechanical) stirring and then cooled to 0°C; (5) was recovered by suction, washed several times with ether, and then dried at 100°C in uacuo. Yield 57 g (91%). For [*I Prof. Dr. R. Okazaki [+I, DipLChem. M. 0-oka,

The Cycloproparenes

“…However, Okazaki and his colleagues have now found (70, 71) that di-iodocycloheptatriene formation is a photochemical reaction. By employing fluorescent light Scheme XIII SNa (X >440 nm) the isolated yield of 1,6-di-iodocycloheptatriene from 1 is increased to 64% (71) while in the complete absence of light only o-iodobenzyl iodide is formed (70). With thiocyanogen, 1 also gives a 1,6-disubstituted cycloheptatriene in high (61%) yield on photolysis (Scheme XIII) (72).…”

“…By employing fluorescent light Scheme XIII SNa (X >440 nm) the isolated yield of 1,6-di-iodocycloheptatriene from 1 is increased to 64% (71) while in the complete absence of light only o-iodobenzyl iodide is formed (70). With thiocyanogen, 1 also gives a 1,6-disubstituted cycloheptatriene in high (61%) yield on photolysis (Scheme XIII) (72). The available evidence clearly implicates radical pathways with I-and -SCN being involved.…”

“…The available evidence clearly implicates radical pathways with I-and -SCN being involved. The 1,6-functionalized cycloheptatrienes obtained by these workers have been utilized (see for example Scheme XIV) for conversion into other valuable, and difficulty accessible, cycloheptatriene derivatives (70)(71)(72), thus demonstrating the synthetic potential of the cycloproparenes.…”

Studies on low‐coordinated nitrogen, phosphorus, sulfur, and selenium compounds

“…As one of the other themes, benzocyclopropene produced photochemically 1,6-diiodo-or -bis(thiocyanato)-1,3,5-cycloheptatriene with I 2 or (SCN) 2 , respectively, and from the products S-containing macrocycles were derived [133].…”

Carbon-hydrogen bond activating reactions of thoracyclobutanes. Routes to unusual actinide-transition metal .mu.-methylene complexes

“…The low-field methylene resonance having VC_H = 124 Hz is typical of a µ-CH, group involving an early transition metal center. 3,4 On the other hand, the upfield displacement and small VC_H (85-95 Hz) of the second methylene resonance suggests an "agostic interaction. "1611,20 The sensitivity of these latter parameters to the identity of the group 4 metal (Zr vs. Hf) implies that the interaction is with that metal.…”