| Abstract
| - A novel chiral and enantiomerically pure phosphole with two (−)-menthyl groups at the2- and 5-positions of the phosphole ring is prepared in two steps, starting from (−)-menthylacetylene, in 67% overall yield. This is the first example of a chiral phosphole inwhich chiral substituents attach directly to the carbon atoms of the phosphole ring. Thephosphole was characterized by X-ray crystallography, and its solid-state structure has nosymmetry, with an envelope-like bent structure for the five-membered ring. The phospholewas readily oxidized into the corresponding phosphole oxide, and reaction with MCl2(cod)(M = Pt, Pd) led to two chiral phosphole−transition-metal complexes, trans-MCl2(phosphole)2,quantitatively. Treatment of the phosphole with metallic lithium in THF cleaved the exocyclicP−Ph bond to give a chiral lithium phospholide with retention of the two (−)-menthylsubstituents. The lithium phospholide was converted into a chiral diphosphole in 62% yieldby reaction with BrCH2CH2Br and into a chiral monophosphaferrocene in 85% yield byreaction with [(η6-mesitylene)FeCp]PF6. A reaction of the phosphole with Mn2(CO)10 inrefluxing xylene gave a chiral phosphacymantrene in 84% yield.
- A novel chiral phosphole in which two (−)-menthyl groups attach directly to the phosphole ring at the 2- and 5- positions has been prepared and converted into a variety of chiral derivatives, including Pt and Pd complexes, phosphaferrocene, and phosphacymantrene. All the compounds were obtained in chiral and enantiomerically pure forms.
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