189508-47-2Relevant academic research and scientific papers
Synthesis of crown ethers based on a spiro acetal framework
Brimble, Margaret A.,Johnston, Andrew D.
, p. 265 - 269 (2007/10/03)
A novel class of crown ether derivatives incorporating a 1,7-dioxaspiro[5.5]undecane ring system have been prepared via alkylation of 3,5-diaxial diol 4 with polyethylene glycol ditosylates [di(toluene-p-sulfonates)]. The complexing properties of these cr
Synthesis and Herbicidal Activity of [3R*, 5S*, 6S*]-3-Benzyloxy-5-methoxy-1,7-dioxaspiro[5.5]undecane and [3R*, 5S*, 6S*]-3-Methoxy-5-benzyloxy-1,7-dioxaspiro[5.5]undecane
Brimble, Margaret A.,Johnston, Andrew D.,Furneaux, Richard H.
, p. 471 - 479 (2007/10/03)
The synthesis of spiroacetals [3R*, 5S*, 6S*]-3-benzyloxy-5-methoxy-1,7-dioaxaspiro[5.5]undecane 3 and [3R*, 5S*; 6S*]-3-methoxy-5-benzyloxy-1,7-dioaxaspiro[5.5]undecane 4, where the substituents on the spiroacetal assembly are in a 1,3-diaxial orientation, is described. Epoxidation of unsaturated spiroacetal 5 using dimethyldioxirane showed greater preference for the α-epoxide 11 over the β-epoxide 12. Treatment of the α-epoxide 11 with lithium diethylamide in tetrahydrofuran afforded both the allylic alcohol 7 and the homoallylic alcohol 13 in approximately equal amounts. Use of a nonpolar solvent (hexane) suppressed the isomerization of the allylic alcohol 7 to the homoallylic alcohol 13, affording a 21:1 ratio of 7:13. Coordination of an oxygen lone pair with the electron-deficient lithium center of the reagent sets up a transition state in which abstraction of a syn-proton and opening of the epoxide leads to stereoselective formation of allylic alcohol 7 with a pseudoaxial hydroxyl group at C-5. The hydroxyl group liberated in the epoxide rearrangement step was then used to direct a second epoxidation to the lower face of the alkene. Thus, treatment of alcohol 7 with m-CPBA buffered with sodium acetate afforded α-syn-epoxy alcohol 9. Subsequent epoxide opening using lithium aluminum hydride proceeded smoothly, affording syn-3,5-diaxial diol 10 and 4,5-diol 22. Epoxy alcohol 9 was then treated with sodium hydride and methyl iodide or benzyl bromide, affording methyl ether 23 or benzyl ether 24, respectively. Reduction of methoxy epoxide 23 with lithium aluminum hydride then afforded alcohol 25 together with the regioisomeric alcohol 27. Benzyloxy epoxide 24 afforded alcohols 29 and 31. Finally benzylation of alcohol 25 afforded bis-ether 3 whereas methylation of alcohol 29 afforded bis-ether 4. Spiroacetals 3 and 4 were screened for herbicidal activity and exhibited significant activity against the weeds Avena fatua, Setaria viridis, Amaranthus retroflexus, and Chenopodium album when applied preemergence. Bis-ethers 3 and 4, which contain alkoxy groups anchored in a 1,3-diaxial orientation on a spiroacetal ring, represent the first examples of herbicides based on a spiroacetal ring system.
Crystal structures of (3S*,4S*,5S*,6S*)-3,4-epoxy-1,7-dioxaspiro[5.5]undecan- 5-ol, (3R*,5S*,6S*)-1,7-dioxaspiro[5.5]undecane-3,5-diyl diacetate and (4S*,5S*,6S*)-1,7-dioxaspiro[5.5]undecane-4,5-diol
Brimble, Margaret A.,Johnston, Andrew,Hambley, Trevor W.,Turner, Peter
, p. 123 - 127 (2007/10/03)
The structures of (3S*,4S*,5S*,6S*)-3,4-epoxy-1,7-dioxaspiro[5.5]undecan- 5-ol (2), (3R*,5S*,6S*)-1,7-dioxaspiro[5.5]undecane-3,5-diyl diacetate (4) and (4S*,5S*,6S*)-1,7-dioxaspiro[5.5]undecane-4,5-diol (5) have been determined by X-ray crystallography. The unsubstituted tetrahydropyran ring in (2) adopts an axial position with respect to the epoxy-substituted ring and the hydroxy group at C 5 is syn to the epoxide group. Intermolecular hydrogen bonding is observed between the C 5 hydroxy group and O1. The two six-membered rings in (4) adopt chair conformations and the two acetate groups adopt 1,3-diaxial positions. The C 5 hydroxy group in (5) assumes an axial position anti to the C-O bond of the neighbouring ring whilst 4-OH occupies an equatorial position. Intermolecular hydrogen bonding is also observed between 4-OH and 5-OH. Compound (2), C9H14O4, M 186.21, crystallized in the monoclinic space group P21/c with a 7.867(1), b 12.2060(9), c 9.3676(8) A, β 102.744(8)°, V 877.4(1) A3 and No 1163 [I > 2.5σ(I)], R 0.031, Rw 0.035. Compound (4), C13H20O6, M 272.30, crystallized in the triclinic space group P1 with a 9.902(1), b 11.0024(9), c 6.9183(5) A, α 104.078(8), β 96.769(9), γ 101.980(8)°, V 703.8(1) A3, No 1657 [I > 2.5σ(I)], R 0.047, Rw 0.044. Compound (5), C9H16O4, M 188.22, crystallized in the orthorhombic space group Pbca with a 25.504(3), b 8.909(2), c 8.038(2) A, V 1826.4(5) A3, No 1096 [I > 2.5σ(I)], R 0.030, Rw 0.030.
Synthesis of a new spiroacetal based herbicide
Brimble, Margaret A.,Johnston, Andrew D.,Furneaux, Richard H.
, p. 3591 - 3594 (2007/10/03)
[3R*, 5S*, 6S*]-3-Benzyloxy-5-methoxy- 1,7-dioxaspiro[5.5]undecane 3 and [3R*, 5S*, 6S*]-3-methoxy-5-benzyloxy-1,7-dioxaspiro[5.5]undecane 4 were prepared making use of a base induced rearrangement of a 4,5-epoxy-1,7-dioxaspiro[5.5]undecane.
