113297-14-6Relevant articles and documents
α-Bromo Spiroketals: Stereochemistry and Elimination Reactions
Lawson, Elvie N.,Kitching, William,Kennard, Colin H. L.,Byriel, Karl A.
, p. 2501 - 2508 (1993)
The simple spiroketals, 1,6-dioxaspirononane (2), 1,6-dioxaspirodecane (5), 1,7-dioxaspiroundecane (6), and (E,E)-2,8-dimethyl-1,7-dioxaspiroundecane (7), have been brominated by bromine in carbon tetrachloride/calcium carbonate or acetic acid, and a number of mono-, di-, and tribromo derivatives have been characterized.The relative stereochemistries have been established by correlated 1H and 13C NMR spectroscopy and X-ray crystal structure determinations.Dehydrobromination with potassium tert-butoxide in either dimethyl sulfoxide or tetrahydrofuran is facile for the axial monobromides, although both axial and equatorial bromides derived from 1,6-dioxaspirodecane (5) and 1,7-dioxaspiroundecane (6) dehydrobromate to provide 1,6-dioxaspirodec-9-ene (35) and 1,7-dioxaspiroundec-4-ene (26), respectively.Hydration of these readily acquired alkenes furnishes the corresponding 9- and 4-ols, respectively, with the latter being components of the rectal glandular secretion of Bactrocera oleae (olive fly), Bactrocera cacumintas, and Bactrocera distincta.These studies indicate that α-bromination of suitable spiroketals may be a viable later step in the synthesis of α-bromine-containing spiroketal metabolites such as obtusin and neoobtusin.
Allylic oxidation of unsaturated spiroketals
Brimble, Margaret A.,Edmonds, Michael K.,Williams, Geoffrey M.
, p. 7509 - 7512 (1990)
Allylic bromination of the bicyclic spiroketals (4a-c) gave predominantly the axial bromides (6), (9) and (12) which underwent SN2 displacement to the equatorial alcohols (7), (11) and (14) respectively using KO2/18-crown-6 in THF/DMSO (10:1).
Allylic functionalization of the 1,7-dioxaspiro[5.5]-undec-4-ene and 1,6,8-trioxadispiro[4.1.5.3]-pentadec-13-ene ring systems
Brimble,Edmonds,Williams
, p. 6455 - 6466 (1992)
Allylic bromination of the bicyclic spiroacetals 5,6 and 7 gave predominantly the axial bromides 15, 21 and 23 which underwent S(N)2 displacement to the equatorial alcohols 17, 22 and 25 respectively, using potassium superoxide and 18-crown-6 in THF/DMSO (10:1). Allylic bromination of the cis-bis-spiroacetal 26 gave predominantly the rearranged allylic bromide 29 which afforded alcohols 30 and 31 resulting from both S(N)2 and S(N)2 displacement upon treatment with potassium superoxide. Bromination of the trans-bis-spiroacetal 27 afforded a complex mixture from which only the non-rearranged bromide 34 could be isolated. This bromide 34 afforded the axial alcohol 37 upon treatment with potassium superoxide.
Gold(I)-, palladium(II)-, platinum(II)-, and mercury(II)-catalysed spirocyclization of 1,3-enynediols: Reaction scope
Zhdanko, Alexander,Maier, Martin E.
, p. 3411 - 3422 (2014/06/09)
The spirocyclization of different 1,3-enynediols was investigated. The reaction was only efficient for the synthesis of [5,6]-spiroacetals. In this case, the reaction was characterized by almost quantitative yields, short reaction times, and low catalyst loadings (0.5-1%). When the synthesis of [6,6]-spiroacetals was attempted, the reaction suffered from poor regioselectivity and a higher propensity of the intermediate dienol ethers to decompose under the acidic conditions, and it became no longer viable. But it is possible to generate the dienol ethers cleanly under milder conditions as a mixture of regioisomers. This striking difference in reaction efficiency was explained by the unstable dienol ethers cyclizing more quickly to give [5,6]-spiroacetals than to give [6,6]-spiroacetals. In this study, the successful application of a new cationic palladium pincer complex for electrophilic alkyne activation at room temperature has been demonstrated for the first time. Copyright
A highly efficient access to spiroketals, mono-unsaturated spiroketals, and furans: Hg(II)-catalyzed cyclization of alkyne diols and triols
Ravindar, Kontham,Sridhar Reddy, Maddi,Deslongchamps, Pierre
supporting information; experimental part, p. 3178 - 3181 (2011/08/06)
Hg(II) salts are identified as highly efficient catalysts for the versatile construction of spiroketals from alkyne diols in aqueous conditions. Monounsaturated spiroketals and furans were accessed with equal ease when propargylic triols (or propargylic d
Au-catalyzed cyclization of monopropargylic triols: An expedient synthesis of monounsaturated spiroketals
Aponick, Aaron,Li, Chuan-Ying,Palmes, Jean A.
supporting information; experimental part, p. 121 - 124 (2009/07/11)
The gold-catalyzed cyclization of monopropargylic triols to form olefin-containing spiroketals is reported. The reactions are rapid and high yielding when 2 mol % of the catalyst generated in situ from Au[P(t-Bu) 2(o-biphenyl)]CI and AgOTf is e
A palladium mediated spiroketal synthesis
Conway, Jeremy C.,Quayle, Peter,Regan, Andrew C.,Urch, Christopher J.
, p. 85 - 88 (2007/10/03)
A Stork-Negishi olefination-coupling sequence has been applied to the synthesis of spiroketals.
Palladium mediated spiroketal synthesis: Application to pheromone synthesis
Conway, Jeremy C.,Quayle, Peter,Regan, Andrew C.,Urch, Christopher J.
, p. 11910 - 11923 (2007/10/03)
Stereospecific Stille coupling reactions of 2-metallo-dihydropyrans with Z-vinyl iodo alcohols and subsequent cyclisation provides rapid access to 1,7-dioxaspiro[5.5]undecane family of spiroketals.
Allenol ether intermediates in the synthesis of 1,7-dioxaspiro [5.5]undec-4-enes and 1,6-dioxaspiro[4.5]dec-3-enes
Kocienski,Whitby
, p. 1029 - 1038 (2007/10/02)
Sequential dialkylation of methoxyallene via the corresponding lithium derivatives gives 1,3-dialkylated methoxyallenes which undergo acid-catalysed ring closure to 1,7-dioxaspiro[5.5]undec-4-enes. Similarly, cyclic allenol ethers (2-vinylidenetetrahydropyrans) generated by rearrangement of 2-alkynyltetrahydropyrans cyclise on treatment with acid to give 1,6-dioxaspiro[4.5]dec-3-enes.
