Dephosphonylation of α-fully substituted β-keto phosphonates with LiAlH4; regioselective alkylation of ketones employing phosphonate as a temporary activating group
作者:Shi Yong Lee、Jong Eoun Hong、Won Bum Jang、Dong Young Oh
DOI:10.1016/s0040-4039(97)00975-1
日期:1997.6
Alkylation of β-keto phosphonates is performed by teatment of β-keto phosphonates with n-BuLi, followed by addition of alkyl halides. The acquired α-fully substituted β-keto phosphonates are dephosphonylated by treatment of the lithium enolates with LiAlH4, followed by quenching with aqueous H2SO4 solution. This whole procedure represents a new route to regioselective alkylation of ketones.
β-酮膦酸酯的烷基化是通过用n -BuLi乳化β-酮膦酸酯,然后添加烷基卤来进行的。通过用LiAlH 4处理烯醇锂,然后用H 2 SO 4水溶液淬灭,将获得的α-完全取代的β-酮膦酸酯脱膦酰化。整个过程代表了酮区域选择性烷基化的新途径。
Surveying approaches to the formation of carbon–carbon bonds between a pyran and an adjacent ring
作者:Jeffrey D. Frein、Tomislav Rovis
DOI:10.1016/j.tet.2006.02.042
日期:2006.5
We have examined several methods for the stereoselective formation of carbon-carbonbonds between contiguous rings where a stereogenic center is already present. The approaches investigated were a [1,3] oxygen to carbon rearrangement of cyclic vinyl acetals, an intermolecular enolsilane addition into an in situ generated oxocarbenium ion, an intramolecular conjugate addition of tethered alkoxy enones
An efficient method is developed for the synthesis of functionalizedbenzimidazoles and perimidines by the condensation of aryl diamines with β‐carbonyl compounds catalyzed by ytterbiumchloride. The reactions give good yields under mild conditions. A mechanism involving a lanthanide activated CCbondcleavage is proposed.
Regiospecific Vinyl Phosphate/β-Keto Phosphonate Rearrangements Initiated by Halogen−Metal Exchange
作者:Tracy J. Baker、David F. Wiemer
DOI:10.1021/jo972131x
日期:1998.4.1
trapping the resulting enolate by reaction with a dialkyl phosphorochloridate gives the 2-bromovinyl phosphate. Metalation can be accomplished upon treatment with n-BuLi, and rearrangement is facile once metalation has been achieved. Studies with isotopically labeled substrates have shown that this rearrangement is regiospecific, in contrast to vinyl phosphate/beta-keto phosphonate rearrangements induced
[2 + 2] Cycloaddition of cyclic vinyl phosphonates with ketenes †
作者:Suzanne M. Ruder、Min Ding
DOI:10.1039/b000014k
日期:——
Highly substituted cyclic β-alkoxyvinyl phosphonates underwent thermal [2+2] cycloaddition with activated ketenes to afford bicyclic phosphonates. Fragmentation of the central polarized bond of this bicyclic system occurred readily upon treatment with zinc in acetic acid, to give rise to ring expanded products. This method provides access to cycloheptane-1,3-diones substituted at the 4-position with