Halo alkynes, reduction

The BINAL-H reduction works well with alkenic - and alkynic ketones affording alcohols with satisfactory optical purities (Scheme It is noteworthy that (S)-BINAL-H [(S)-(28)] reduces 1-halo-l-octen-3-one and 2-cyclopentene-l,4-dione to give the corresponding carbinols, which are important chiral building blocks for the synthesis of prostaglandins by the conjugate addition approach. ... 

The ruthenium example probably involves oxidative addition of the di-halide to two Ru(CO)3 fragments derived from the photolysis of the cluster then the metals probably disproportionate, so that one becomes the observed product and the other carries away the halides in the form of undefined Ru(II) halo complexes. The reaction of Eq. 5.32 probably goes by an oxidative coupling to give 5.20, which is very favorable for alkynes, followed by a reductive elimination of the cyclobutadiene ligand. 

During the course of some work aimed at the selective reduction of a substituted alkyne to the c/5-alkene, Olsen et al have discovered the novel synthesis of a rare ring system. Lithiated alkynes were found to react with the halo-substituted phthalimide (360) at the carbonyl group rather than at the halogen-bearing carbon as expected. The intermediate cyclized to this position to give an oxazolo[2,3-a] isoindole (361). 

---