Cl-BODIPYs, synthesized in high yields from dipyrrins under air- and moisture-free conditions, are extremely facile to substitution at boron compared to their corresponding F-BODIPYs, opening up a new route to BODIPYs functionalized at boron.

A new method for the synthesis of Cl-BODIPYs from F-BODIPYs is reported, merely requiring treatment of the F-BODIPY with boron trichloride. Cl-BODIPYs are exploited as synthetic intermediates generated in situ for the overall conversion of F-BODIPYs to O- and C-BODIPYs in high overall yields using a mild one-pot procedure. This route enables F-BODIPYs to be transformed into derivatives that are not accessible via the direct route, as demonstrated via the use of 1,3-propanediol.

The first use of phosphenium cations in asymmetric catalysis is reported. A diazaphosphenium triflate, prepared in two or three steps on a multigram scale from commercially available materials, catalyzes the hydroboration or hydrosilylation of cyclic imines with enantiomeric ratios of up to 97:3. Catalyst loadings are as low as 0.2 mol %. Twenty-two aryl/heteroaryl pyrrolidines and piperidines were prepared using this method. Imines containing functional groups such as thiophenes or pyridyl rings that can challenge transition-metal catalysts were reduced employing these systems.

An improved and scalable synthesis of the unsubstituted 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene framework facilitates access to the previously unreported parent dipyrrin HCl salt, as well as 4,4-dichloro-4-bora-3a,4a-diaza-s-indacene.

The activation of F-BODIPYs with boron trihalides, followed by treatment with a nucleophile, effects facile substitution at boron; using water as the nucleophile promotes deprotective removal of the -BF2 moiety and thereby production of the corresponding parent dipyrrin salt in quantitative yield under extremely mild conditions.