A two-step synthesis of allylic syn 1,3-diols via an intramolecular oxa-Michael reaction followed by a modified Julia olefination

An Efficient Synthesis of Vinyl Sulfones from Alkenes and Aryl Sulfinates¹

“…The vinyl sulfone products derived from the former type of compounds have important synthetic uses. 8 An a,b-unsaturated ketone afforded a minor amount (7%) of the corresponding Michael addition product ( Table 1, entry 3). Various functional groups such as halogen, hydroxy, amine, carbonyl, Cbz, Bn, and PMB remained unchanged.…”

Trisubstituted Highly Activated Benzo[d]thiazol-2-yl-sulfone-Containing Olefins as Building Blocks in Organic Synthesis

“…1 H NMR and 13 C{ 1 H} NMR spectra were measured on Jeol ECA400II (400 and 101 MHz) or Jeol 500 ECA (500 and 126 MHz) in CDCl 3 or dimethyl sulfoxide (DMSO). Chemical shifts are reported in ppm, and their calibration was performed (a) in case of 1 H NMR experiments on the residual peak of non-deuterated solvent δ (CHCl 3 ) = 7.26 ppm; δ (DMSO) = 2.50 ppm, (b) in case of 13 C NMR experiments on the middle peak of the 13 C signal in deuterated solvent δ (CDCl 3 ) = 77.2 ppm; δ (DMSOd 6 ) = 39.5 ppm, and (c) in case of 19 F{ 1 H} NMR experiments on the external calibrant CFCl 3 [δ (CFCl 3 ) = 0 ppm]. Proton coupling patterns are represented as singlet (s), doublet (d), doublet of doublet (dd), triplet (t), triplet of triplet (tt), and multiplet (m).…”

“…At the same time, the use of heteroaryl vinyl sulfones as powerful electrophilic substrates was somewhat limited. Only roughly a dozen of seminal works (for selected examples see Scheme ) focusing on the use of vinyl and/or 1,2-disubstituted olefin-bearing heteroaryl sulfones were reported. − Such olefins proved to be highly superior in their reactivity in comparison to aryl vinyl sulfones and even to 1,1-diphenylvinylsulfones . We speculated that additional substitution with the electron-withdrawing (EWG) group on heteroaryl vinyl sulfone should broaden the synthetic utility of the vinyl sulfones (Figure ).…”

Synthesis of 1,3-Diols by O-Nucleophile Additions to Activated Alkenes

“…In an attempt to optimize the synthesis of protected syn 1,3-diols with an α-olefin, Prunet and Oriez developed the oxa-Michael reaction on heteroaryl vinyl sulfones. 12 A careful selection of the reaction conditions is needed in order to avoid unwanted Julia olefination with benzaldehyde. For benzothiazolyl sulfones, LiHMDS proved to be the best base, while the use of potassium bases led to poor conversions and selectivities (Scheme 6).…”