Dihydroxylation of 4-Substituted 1,2-Dioxines: A Concise Route to Branched Erythro Sugars
作者:Tony V. Robinson、Daniel Sejer Pedersen、Dennis K. Taylor、Edward R. T. Tiekink
DOI:10.1021/jo900669u
日期:2009.7.17
The synthesis of 2-C-branched erythritol derivatives, including the plant sugar (+/-)-2-C-methylerythritol 2, was achieved through a dihydroxylation/reduction sequence on a series of 4-substituted 1,2-dioxines 3. The asymmetric dihydroxylation of 1,2-dioxines was examined, providing access to optically enriched dihydroxy 1,2-dioxanes 4. The synthesized 1,2-dioxanes were converted to other erythro sugar analogues and tetrahydrofurans through controlled cleavage of the endoperoxide linkage.
Sensitized photo-oxygenation of a wide variety of acyclic 1,3-dienes was investigated. The 1,4-cycloaddition of singlet oxygen to acyclic conjugated dienes was closely related to the thermal Diels-Alder reaction in stereospecificity, and steric and electronic effects of substituents. Reactivity order of singlet oxygen toward conjugated dienes and isolated C—C double bonds was exhibited as follows:
Synthesis of 1<i>H</i>-Cyclopropa[<i>b</i>]naphthalenes<i>via</i>Trapping of<i>o</i>-Benzoquinodimethanes
作者:Paul Müller、Domingo Rodriguez
DOI:10.1002/hlca.19850680423
日期:1985.6.26
1H-Cyclopropa[b]naphthalene (10a) and 3-methyl or dimethyl derivatives have been synthesized by interception of appropriately substituted o-quinodimethanes 3 with 1-bromo-2-chlorocyclopropene 5, and subsequent dehydrohalogenation of the adducts. The o-quinodimethane derivatives 3 in turn were obtained from the diynes 7via base-induced isomerization to bisallenes 8 and thermal electrocyclic ring closure
通过用1-溴-2-氯环丙烯5拦截适当取代的邻喹啉甲烷3,然后加合物脱氢卤化,合成了1 H-环丙烷[ b ]萘(10a)和3-甲基或二甲基衍生物。所述Ô -quinodimethane衍生物3依次从该二炔得到7通过碱诱导的异构化,以bisallenes 8和热电环化环合。