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X-ray crystallographic studies of four photoreactive tetrahydronaphthoquinol derivatives and five related compounds

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Title: X-ray crystallographic studies of four photoreactive tetrahydronaphthoquinol derivatives and five related compounds
Author: Secco, Anthony Silvio
Degree Doctor of Philosophy - PhD
Program Chemistry
Copyright Date: 1982
Subject Keywords X-ray crystallography
Abstract: The structures of four 4aβ,5,8,8aβ-tetrahydro-1 -naphthoquin-4-ol derivatives have been studied and related to their observed photochemical reactivity. H-abstractions are dominant in the solid state photolyses of these compounds because of their conformations and the topochemical control by the lattice. All structures have been solved by direct methods and refined by least squares procedures. The 2,3,6,7-tetramethyl-4α-ol derivative, C₁₄H₂₀O₂, is monoclinic, space group C2/c, a = 13.898(3), b = 5.228(1), c = 17.316(3) Å, β = 97.442(7)° and Z = 4. This structure was refined to R = 0.058 for 888 reflections. The 2,3- and 6,7-dimethyl-4α-ol compounds-C₁₂H₁₆O₂, are orthorhombic, space group P2₁2₁2₁, and monoclinic, space group 2₁/c, respectively. For the 2,3-derivative, a = 5.148(1), b = 12.269(2), c = 16.478(3) Å, Z = 4 and the refinement of 671 data led to an R of 0.031. The 6,7-compound, a = 9.242(3), b = 22.724(3), c = 5.139(2) Å, β = 102.7(1)°, Z = 4, was refined to R = 0.032 for 626 data. 2,3,4σ,4aβ,6,7,8aβ-heptamethyl-4β-ol, C₁₇H₂₆0₂, is monoclinic, space group P2₁/c, a = 7.497(2), b = 16.792(3), c = 12.687(3) Å, β = 105.30(1)° and Z = 4. An R-value of 0.041 was obtained from the refinement of 1934 reflections. The above compounds have similar conformations which are favorable to H-abstraction reactions. The 6,7-dimethyl-1α,4α-diol C₁₂H₁₈0₂, crystallizes in the monoclinic system, space group P2₁/c, a = 13.870(2), b = 18.025(4), c = 9.236(1) Å, β = 108.098(6)° , Z = 8 and was refined to R = 0.032 for 1461 reflections. The diol compound adopts the same conformation as those above but is not photoreactive. The following four compounds were derived from either tetrahydronaphthoquinol progenitors or their oxidized forms, tetrahydronaphthoquinones. A twistane-1ike structure, twistenone C₁₀H₁₀0₂, was found to crystallize in the monoclinic system, space group P2₁/n, a = 6.381(2), b = 19.454(2), c = 6.708(2) Å, β = 1 06.24( 1 )° and Z = 4. Refinement of 930 reflections converged at R = 0.037. 5-(2,3-dimethylphenyl)-ƴ-butyrolactone crystals, C₁₂H₁₅O₂ are monoclinic, space group P2₁/n, a = 10.847(3), b = 6.924(1), c = 13.654(4) Å, β = 95.22(1)° and Z = 4. The structure was refined to R = 0.057 for 569 reflections. It was hoped that elucidation of this structure would aid in determining the intermediate compound from which it was formed. The methylene ketone C₁₇H₂₄0, derived from the acetylation product of the previously described heptamethyl-4β-ol, is monoclinic, space group P2₁/a, a = 12.374(2), b = 8.771(1), c = 13.743(2) Å, β = 104.027(6)° , Z = 4 and refined to R = 0.037 for 1369 data. A reaction designed to pinacolize a diketone cage compound resulted in a different product from which the hydroxy mesylate derivative C17H280„S, was formed. The crystals are monoclinic, space group P2,/c, a = 9.246(2), b = 10.938(1), c = 17.335(4) Å, β = 102.11(1)° and Z = 4. Refinement converged at R = 0.042 for 2995 reflections.
URI: http://hdl.handle.net/2429/23649
Series/Report no. UBC Retrospective Theses Digitization Project [http://www.library.ubc.ca/archives/retro_theses/]
Scholarly Level: Graduate

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