Enantioselective Synthesis of 3,3-Difluoropyrrolidin-4-ol, a Valuable Building Block in Medicinal Chemistry.

In this paper, we report for the first time two enantioselective routes to 4,4-difluoropyrrolidin-3-ol, a valuable building block in medicinal chemistry. In the first route, we took advantage of the C2 symmetry of (3R,4R)-3,4-dihydroxypyrrolidine in which the desired chirality was derived from the chiral pool (l-(+)-tartaric acid). In the second route, we efficiently assembled the pyrrolidine ring in the presence of a gem-difluoro moiety to avoid using potentially hazardous deoxofluorinating reagents and subsequently introduced the chirality by a stereoselective iridium-diamine-catalyzed asymmetric transfer hydrogenation reaction.

The domino chemistry approach to molecular complexity: competing domino processes modulated by the substitution pattern.

Oxidative cleavage with lead tetraacetate results in the synthesis of different oxygen heterocycles starting from the same unsaturated 1,2-diol of type I by tuning of the substitution pattern at the angular position. When this compound bears a functional substituent, such as an alkoxy, ester, alkenyl, or simply a hydrogen, more than one reaction pathway are in competition. The process allows for the selective formation of three different complex ring systems, by the appropriate choice of the angular substituent, leading to either a ring-expanded type 1, ring-retained type 2, or domino products 3.

An efficient one-pot approach to bridged bicyclic ring-systems through consecutive hetero-domino transformations: a mechanistic rationale and further rearrangements.

This article describes the design of olefin-generated/reagent-modulated consecutive hetero-domino reactions of 1,2-unsaturated bicyclic diols, which are potentially of great use, initiated by PhI(OAc)(2), continued by [Pb(OAc)(4)], and completed by use of a mild base (K(2)CO(3)). Inversion of a quaternary center has been achieved through a three-reaction sequence: a domino transformation followed by an m-CPBA-mediated Baeyer-Villiger oxidation and subsequent reductive lactone ring opening.