Synthesis of β-oxo carbonyl and thiocarbonyl compounds via basic sulfur abstraction
作者:Saúl Silva、Christopher D. Maycock
DOI:10.1016/j.tet.2019.130552
日期:2019.10
suitable thioesters represents a mild method for the formation of carbon-carbon bonds and the formation of 1,3-dicarbonyl compounds. A study of the scope and limitations of this reaction for the synthesis of these or mixed 1,3-carbonyl/thiocarbonyl compounds by a base promoted sulfur abstraction rearrangement is described. These reactions were typically very clean and the products were obtained in good
α-Chlorination of ketones using p-toluenesulfonyl chloride
作者:Kay M. Brummond、Kirsten D. Gesenberg
DOI:10.1016/s0040-4039(99)00213-0
日期:1999.3
Treatment of a variety of ketones with lithium diisopropylamide followed by p-toluenesulfonylchloride gives α-chloroketones in good yields. In addition, a polymer tosyl chloride reagent has also been shown to effect this transformation.
Here we describe the realization of a one-pot protocol for the β-C–H halogenation of cyclic enones via umpolung of the β-carbon. The developed method includes hydrazone formation and selective β-halogenation (bromination, chlorination) with N-bromosuccinimide and Palau’chlor (2-chloro-1,3-bis(methoxycarbonyl)guanidine) followed by hydrolysis of the hydrazone moiety. Using the optimized conditions,
Unusual Reagent Control of Diastereoselectivity in the 1,2-Addition of Hard Carbon Nucleophiles to C<sub>6</sub>-Heteroatom Substituted Cyclohexenones
作者:Harriet A. Lindsay、Catherine L. Salisbury、Wally Cordes、Matthias C. McIntosh
DOI:10.1021/ol016673j
日期:2001.12.1
text] A surprising and synthetically useful counterion-dependent reversal of diastereoselectivity was found in 1,2-additions of hard carbonnucleophiles to C(6)-heterosubstituted cyclohexenones. In general, Grignard reagents added syn to the C(6)-substituent and Li reagents added anti, although some exceptions were found. Selectivities could be increased in some cases by appropriate choice of solvent and/or
A concise route to the tetracyclic core of phorbol
作者:Leo A. Paquette、Daryl R. Sauer、Scott D. Edmondson、Dirk Friedrich
DOI:10.1016/s0040-4020(01)86705-3
日期:1994.4
The tetracyclic ketone 17, which possesses a framework closely related to phorbol, has been prepared in enantiomerically pure condition. Condensation of the dichlorocerate derived from 3 with 2-chlorocyclohexanone leads to chlorohydrins 4 and 5 in a 1:1 ratio. Treatment of 5 with excess vinylmagnesium bromide delivers 7, thereby setting the stage for anionic oxy-Cope rearrangement to 9. Epoxidation