Multisubstituted α,β-Unsaturated γ-Lactones from 1-Chlorovinyl p-Tolyl Sulfoxides and tert-Butyl Carboxylates Using Pummerer-Type Cyclization as the Key Reaction
作者:Tsuyoshi Satoh、Takashi Katae、Shimpei Sugiyama
DOI:10.1055/s-0030-1259987
日期:2011.5
The addition reaction of 1-chlorovinyl p-tolyl sulfoxides, derived from aldehydes and chloromethyl p-tolyl sulfoxide, with the lithium enolate of tert-butyl carboxylates gave adducts in quantitative yields. Treatment of the adducts with trifluoroacetic anhydride in the presence of sodium iodide resulted in the formation of γ-lactones bearing a p-tolylsulfanyl group at the γ-position through Pummerer-type cyclization. Oxidation of the sulfanyl group to the sulfinyl group followed by thermal syn-elimination gave α,β-unsaturated γ-lactones (γ-butenolides) in moderate to good yields. Trapping the intermediates of the addition reaction with iodoalkanes gave alkylated adducts, from which α,γ- and β,γ-disubstituted γ-butenolides were obtained. These procedures provide a good way to synthesize multisubstituted γ-butenolides from aldehydes.
由醛和氯甲基对甲苯亚砜衍生的1-氯乙烯基对甲苯亚砜与叔丁基羧酸锂烯醇的加成反应,以定量产率得到了加成物。在碘化钠存在下,将这些加成物与三氟乙酸酐处理后,通过Pummerer型环化反应形成了在γ位带有对甲苯硫基的γ-内酯。将硫基氧化为亚砜基,随后进行热顺式消除反应,得到中等到良好产率的α,β-不饱和γ-内酯(γ-丁烯内酯)。通过碘烷捕获加成反应的中间体,得到烷基化加成物,从中获得了α,γ-和β,γ-二取代的γ-丁烯内酯。这些方法为从醛合成多取代的γ-丁烯内酯提供了一条有效途径。