Search Results (3)

Hydroxymethyl 1,3-diol motifs are common structural motifs in natural products, particularly in polypropionates with important therapeutic potential. However, general and complementary methods for their regio- and diastereoselective synthesis remain limited. In this study, we expanded a second-generation epoxide-based methodology involving the regioselective cleavage of TIPS-monoprotected cis- and trans-2,3-epoxy alcohols using alkenyl Grignard reagents. Regioselective ring opening of cis-epoxides provided anti-1,3-diols, while trans-epoxides afforded the corresponding syn-1,3-diols. The use of cis-propenylmagnesium bromide and vinyl Grignard reagents enabled direct access to cis- and terminal homoallylic 1,3-diols, respectively, with moderate to good yields (46–88%) and excellent regioselectivities (95:5). In contrast, reactions with trans-propenyl Grignard reagent led to partial alkene isomerization, limiting their synthetic utility. To address this, a complementary two-step approach employing propynyl alanate addition followed by sodium/ammonia reduction was incorporated, providing access to trans-homoallylic 1,3-diols with high diastereoselectivity. All 1,3-diols were characterized by NMR spectroscopy, confirming regioselective epoxide opening. These combined strategies offer a practical and modular platform for the synthesis of syn- and anti-hydroxymethylated 1,3-diols and their application to the construction of polypropionate-type fragments, supporting future efforts in the total synthesis of polyketide natural products. Full article

Carbon–carbon bond formation is one of the most important tools in synthetic organic chemists’ toolbox. It is a fundamental transformation that allows synthetic chemists to synthesize the carbon framework of complex molecules from inexpensive simple starting materials. Among the many synthetic methodologies developed for the construction of carbon–carbon bonds, organocopper reagents are one of the most reliable organometallic reagents for this purpose. The versatility of organocuprate reagents or the reactions catalyzed by organocopper reagents were demonstrated by their applications in a variety of synthetic transformations including the 1,4-conjugate addition reactions. Sulfur-containing heterocyclic compounds are a much less studied area compared to oxygen-containing heterocycles but have gained more and more attention in recent years due to their rich biological activities and widespread applications in pharmaceuticals, agrochemicals, and material science. This paper will provide a brief review on recent progress on the synthesis of an important class of sulfur-heterocycles-2-alkylthiochroman-4-ones and thioflavanones via the conjugate additions of Grignard reagents to thiochromones catalyzed by copper catalysts. Recent progress on the synthesis of 2-substituted thiochroman-4-ones via alkynylation and alkenylation of thiochromones will also be covered in this review. Full article

A series of unsymmetrically substituted oligosilanes were synthesized via stepwise introduction of different substituents to α-chloro-ω-hydrooligosilanes. The reactions of α-chloro-ω-hydrooligosilanes with organolithium or Grignard reagents gave hydrooligosilanes having various alkyl, alkenyl, alkynyl and aryl groups. Thus-obtained hydrooligosilanes were converted into alkoxyoligosilanes by ruthenium-catalyzed dehydrogenative alkoxylation with alcohols. Full article