General approach for the synthesis of polyquinenes via the weiss reaction. Preparation of the chiral tetracyclo [6.6.0.01,5.08,12]tetradecane-3,6,10,13,-tetraene

The aldol approach to construct the tetracyclic polyquinane skeleton of $\text{12}$, followed by hydroboration and the HMPA mediated dehydration of four hydroxyl groups has resulted in the facile synthesis of the chiral polyquinene, tetracyclo[6.6.0.0^1,5.0^8,12]-tetradecane-3,6,10,13-tetraene $\text{2}$. This method completely avoids the troublesome fragmentation reactions earlier encountered when the strained tetraone $\text{9}$ was reacted with nucleophilic reagents.     

A synthetic entry into tetracyclo (4.2.0.02,4.03,8) octane system

Novel ceric ion oxidation of homocubanone provides a facile entry into tetracyclo(4.2.0.0^2,4.0^3,8)octane and tricyclo (3.3.0.0^2,7)octane ring systems.     

Molecular structure of methyl-10,14,19,19-tetramethyl-4-oxo-20-oxahexacyclo [15.3.1.16.18.06.15.09.14017.21]docosane-10-carboxylate

The synthesis of methyl-10,14,19,19-tetramethyl-4-oxo-20-oxahexacyclo[15.3.1.1^6.18.0^6.15.0^9.140^17.21] docosane-10-carboxylate III is performed and its molecular structure is determined. Compound III C₂₇H₄₀O₄ crystallizes in the monoclinic system with the cell parameters as follows: a = 12.8081(11) ?, b = 7.0384(6) ?, c = 12.8904(12) ?, β = 105.828(2)^o, P2₁ space group, Z = 2, d = 1.273 mg/m³.     

Molecular and crystal structure of 23,24,25,26,27,29,30-heptamethyl-19,28-oxahexacyclo[15.13.18.017,18.013,14.08,9.05,10]tetracos-3-yl acetate

The molecular structure of 23,24,25,26,27,29,30-heptamethyl-19,28-oxahexacyclo[15.13.18.0^17,18.0^13,14.0^8,9.0^5,10]tetracos-3-yl acetate III. Compound III C₃₂H₅₂O₃ crystallizes in the monoclinic crystal system with the unit cell parameters a = 13.265(15) ?, b = 6.481(7) ?, c = 32.274(4) ?, β = 99.333(2)°, space group C2, Z = 4, d = 1.176 g/cm³. Original Russian Text Copyright ? 2009 by N. I. Medvedeva, O. B. Flechter, and A. A. Korlyukov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 2, pp. 399–401, March–April, 2009.     

General approach for the synthesis of polyquinanes

The diborane-mediated reduction of labile β-diketones 4, 5 and 6 has been employed as the key step in the synthesis of the three polyquinanes, all-$\text{cis}$-tetracyclo-[6.6.0.0^1,5.0^8,12]tetradecane 1, all-$\text{cis}$-tricyclo[6.3.0.0^1,5]undecane 2 and all-$\text{cis}$-tetracyclo-[5.5.1.0^4,13.O^10,13]tridecane, staurane 3, respectively.     

Mechanism of the thermal conversion of tetracyclo[3.3.0.02,4.0.3,6]oct-7-ene into dihydropentalenes

One of a number of possible mechanisms has been established for the title reaction.