Impact of high-lying .sigma. orbitals and extensive through-bond interaction on chemical reactivity. 1. Convenient syntheses of hypostrophene and its susceptibility to rearrangement under electrophilic conditions

Orbital interactions. 6. The Birch reduction as a tool for exploring orbital interactions through bonds. Through-three-bond interactions

“…Specific details concerning individual competitive studies may be obtained from the authors upon request. Briefly, the product mixtures resulting from the competitive reductions of the following substrates were analyzed as indicated: exo-16 (column E, 70-120 °C at 4 °C/min; held at 120 °C for 10 min, then increased to 170 °C at 4 °C/min and held at this temperature); endo-16 (column E, same conditions as for exo-16); exo-18 (column B, 150 °C); endo-18 (column B, 150 °C); exo-19 (column B, 150 °C); endo-19 (column B, 150 °C); 20 (column A, 90 °C); 21 (column D, 25 °C isothermal, flow rate 10 mL min-1); 22 (column A, 60 °C); toluene (column A, 30 °C). MOs classified with respect to the appropriate (pseudo)symmetry element which interchanges the interacting orbitals.…”

Selective reductive dimerization of homocubane series oximes

“…Pentacyclo[5.3.0.0 2,5 .0 3,9 .0 4,8 ]decan-6-one (X) was obtained from 5.5 g (0.029 mol) of ketal IX by the method [17]. Yield 4.1 g (97%), mp 126-127°C.…”

“…It turned out that bisethylene ketal of 1,9-dibromope ntacylo[5.4.0.0 2,6 .0 3,10 .0 5,9 ]undeca-8,11-dione (ІV) was hydrolyzed by a mixture of 10% sulfuric acid and THF at the ratio 4:1, v/v, at 80°С [17] to form quantitatively a mixture of monoethylene ketals without the admixture of diketone I. Evidently the hydrolysis of one ethylene ketal protective group proceeds relatively easily due to the considerale stain in compound ІV arising from the sterical repulsion of the oxolane moieties which is absent in monoketals ІІ and ІІІ. In turn, the hydrolysis of the second group is impeded by the presence of a bromine in the α-position with respect to the carbonyl substituent.…”

Convenient preparative synthesis of pentacyclo[5.3.0.02,5.03,9.04,8]decane (C 2-Bishomocubane)

“…Only at the hydrolysis in the mixture of 10% sulfuric acid and THF in the ratio 4:1, v/v, at 80°C [11] we succeeded in attainment of the complete hydrolysis of ketal V to ketone VI.…”

“…The reaction product was extracted from the water solution into dichloromethane, the extract was dried with Na 2 SO 4 , the solvent was distilled off in a vacuum. ]decan-10-one (VI) was obtained from 3.53 g (0.019 mol) of ketal V by procedure [11]. Yield 2.66 g (98%), mp 111-112°C.…”