Regioselective Synthesis of 2-Hydroperoxy-2-methylenebutanoic Acid Derivatives via Photooxygenation of Tiglic Acid Derivatives
作者:Waldemar Adam、Axel Griesbeck
DOI:10.1055/s-1986-31871
日期:——
Photooxygenation of (E)-2-methyl-2-butenoic acid derivatives (tiglic acid derivatives) in tetrachloromethane in the presence of catalytic amounts of tetraphenylporphine affords 3-hydroperoxy-2-methylenebutanoic derivatives in generally high yields. Acid-catalyzed cyclodehydration of the 3-hydroperoxy-2-methylenebutanoic acid thus obtained readily gives 5-methyl-4-methylene-3-oxo-1,2-dioxolane, a peroxylactone, in 61% yield. The analogous cyclodehydration of 3-hydroperoxy-2-methylenebutanal [generated in situ by oxygenation of (E)-2-methyl-2-butenal] leads to the formation of 3-hydroxy-5-methyl-4-methylene-1, 2-dioxolane.
Regioselective reaction of singlet oxygen with α,β-unsaturated esters
作者:Michael Orfanopoulos、Christopher S. Foote
DOI:10.1016/s0040-4039(00)98279-0
日期:1985.1
The reaction of singletoxygen with α,β-unsaturated esters shows a general preference for hydrogen abstraction on the alkyl group geminal to the ester.
单线态氧与α,β-不饱和酯的反应显示出一般优先选择与该酯成对的烷基上的氢。
A New Experimental Protocol for Intrazeolite Photooxidations. The First Product-Based Estimate of an Upper Limit for the Intrazeolite Singlet Oxygen Lifetime
作者:Andrea Pace、Edward L. Clennan
DOI:10.1021/ja027053w
日期:2002.9.1
interior of the zeolite was documented. The nearly identical reaction rates in the two slurry solvents are attributed to a leveling of the singletoxygenlifetime by the zeolite framework. A consideration of the rates of the various intrazeolite processes was used to estimate an upper limit for the intrazeolite lifetime of singletoxygen.
Enzymatic preparation of optically active α-methylene β-lactones by lipase-catalyzed kinetic resolution through asymmetric transesterification
作者:Waldemar Adam、Peter Groer、Chantu R. Saha-Möller
DOI:10.1016/s0957-4166(97)00054-2
日期:1997.3
The lipase-catalyzed asymmetric transesterification of racemic α-methylene β-lactones 1 with benzyl alcohol in organic media afforded the opticallyactive β-lactones and the corresponding β-hydroxy esters 2 in excellent enantiomeric excess (ee 95–99%).
Photooxidations of Alkenes in Fluorinated Constrained Media: Fluoro-organically Modified NaY as Improved Reactors for Singlet Oxygen “Ene” Reactions
作者:Andrea Pace、Paola Pierro、Silvestre Buscemi、Nicolò Vivona、Edward L. Clennan
DOI:10.1021/jo0625047
日期:2007.3.1
Creating a stationary fluorinated environment inside the zeolite cavity can increase the reactivity observed for intrazeolite photooxidation of alkenes. Exchanging the zeolite with fluorinated organic cations is a much more effective strategy than simply using a fluorinated solvent for slurry irradiations. Use of cations containing C-F bonds is also more efficient than use of deuterated cations for creation of a singlet oxygen friendly environment where the quenching processes are slowed down. Doping the zeolite with fluoro-organic cation 4 resulted in an increase in the singlet oxygen lifetime to 12 mu s.