Application of the Stereoselective Diels-Alder Reaction of Enantiopure 2-Sulfinyl Dienes: Synthesis of (-)-(1S,5R)-Karahana Ether

Sulfinyl-Mediated Stereoselective Overman Rearrangements and Diels-Alder Cycloadditions

Sulfinyl trichloroacetamides are readily obtained in excellent yields through a highly stereoselective Overman rearrangement. Related bis-allylic substrates lead to amido 2-sulfinyl butadiene derivatives in excellent yields, with total chemo- and diastereoselectivity. These amido dienyl sulfoxides undergo highly selective Diels-Alder cycloadditions with N-phenylmaleimide with remarkable stereocontrol by the sulfoxide moiety.

Recent Advances in the Synthesis of Carotenoid-Derived Flavours and Fragrances

Carotenoids are important isoprenoid compounds whose oxidative degradation produces a plethora of smaller derivatives, called apocarotenoids, which possess a range of different chemical structures and biological activities. Among these natural products, compounds having less than 15 carbon atoms in their frameworks are often relevant flavours or fragrances and their manufacturing represents an important economic resource for chemical companies. The strict correlation between stereochemical structure and odour has made the stereospecific synthesis of the latter biological active compounds increasingly important. In this review, the recent advances on the synthesis of the most relevant carotenoid-derived flavours and fragrances are discussed. In particular, the new synthetic methods that have given new and innovative perspectives from a scientific standpoint and the preparative approaches that might possess industrial importance are described thoroughly.

Highly Diastereoselective Diels-Alder Reactions with Enantiopure Sulfinyl-Substituted 1-Hydroxymethyldienes

Enantiopure hydroxy-2- and -3-sulfinyldienes undergo highly selective Diels-Alder cycloadditions with various dienophiles controlled by the chiral sulfur atom. The related hydroxy-2-sulfonyldienes display complementary pi-facial selectivity.