ChemInform Abstract: Toward the Synthesis of Modified Carbohydrates by Conjugate Addition of Propane‐1,3‐dithiol to α,β‐Unsaturated Ketones.

Abstract

Propane-1,3-dithiol to α,β-Unsaturated Ketones. -MeONa-mediated addition of dithiol (II) to alkynes (I) is accompanied by an intramolecular cyclization to afford spiro compounds (III), which can be regarded as partly modified furanose derivatives. Standard transformations of the corresponding non-cyclized dithians (VII) afford compounds (VIII), which are versatile precursors to a number of modified carbohydrates, such as (IX) and (XI). -(VALDERSNES, S.; APELAND, I.; FLEMMEN, G.; SYDNES*, L. K.; Helv. Chim. Acta 95 (2012) 11, 2099-2122, http://dx.

Conjugated Ynones in Organic Synthesis

“…32,349,417 A few alkanethiols 415 and dithiols 45−48,349,414−416 have been applied, but also some thiophenols. 32,244,417 Furthermore, most reactions have been carried out at room temperature or below, [45][46][47]414,416 but heating as high as 80 °C has also been reported. 244,417 The products obtained from conjugate addition of thiols to ynones depend on the number of thiol groups available per ynone moiety.…”

“…When ynones 71 are treated with propane-1,3-dithiol in a 1:1 molar ratio, the corresponding 1,3-dithiane was obtained. This reaction, developed by Ley and his group, is in general clean and gives the products (502) in excellent yields, [45][46][47]414,416 but if the ynone contains a second electrophilic site, such as a formyl group (503), 1,3-dithiane formation may be followed by cyclization, which is the case when 503 is converted to spirocompound 504 (Scheme 219). 45 The transformation became a most valuable tool for Ley and co-workers who introduced keto functions in specific positions in key fragments of natural products, 45−47 for instance, when ynones 505 were transformed into dithianes 506 in high yields as parts of syntheses of spongipyrans (Scheme 220).…”