Novel Routes to 1,2-Diphosphete and 1,2,4-Triphospholyl π-Complexes

Rock around the Ring: An Experimental and Theoretical Study of the Molecular Dynamics of Stannyltriphospholes with Chiral Tin Substituents

“…[4][5][6] If a λ 3 -phosphorus atom of a phosphole is bonded to a metallic group 14 or another p-block element, a diene-like character of the five-membered heterocycle results because of the covalent character of the P-M bond. [7,8] As the dynamic behaviour of phospholes involves reversible forming and breaking of P-M and probably of C-M bonds, it also reveals details of the bonding situation in the heterocycles. A facile [1,5]sigmatropic shift has been observed by dynamic NMR spectroscopy for the SnPh 3 group of 1-(triphenylstannyl)-2a,b,d and 7b,c confirm the stereochemical interpretations of their spectroscopic data with the help of absolute structure parameter determinations.…”

“…[7] In the former the stannyl group would oscillate between the two adjacent phosphorus atoms like a windscreen wiper, whereas in the latter it rocks around the P 2 edge of 1 or maybe even around the complete π-system of the molecule. Besides simply shifting the substituent to the other P atom through a triangular η 2 transition state, the windscreen-wiper mode could also include a ring-slippage mechanism via η 1 -η 3 -η 5 bonding of the tin atom, as observed earlier for nickel, [9] although in this case an inversion of the pyramidal phosphorus atom would be excluded.…”

“…The target asymmetrically substituted 1-stannyl-1,2,4-triphospholes are also relevant to an interesting preparative question: a high-yield, highly diastereoselective cycloaddition reaction of 1 with two equivalents of the P-alkyne tBuCϵP gives access exclusively to one pair of enantiomeric P 5 (CR) 4 (SnR 3 ) cage compounds with seven stereogenic centres. [7] Control of the stereochemistry of such cageforming processes is one of the main objectives of this research. To the best of our knowledge, no asymmetric P-C cage compounds with a defined stereochemistry are known.…”

Optically active P5-deltacyclenes: selective oxidation, ligand properties, and a diastereoselective rearrangement reaction

“…21 This finding corresponds to the excellent diastereoselectivity of chiral P-C cage forming reactions, which are based on Beckers tert-butylphosphaalkyne 1. [1][2][3][4][5]8,9 Both can be related to the big size difference of the t-Bu substituent of the carbon atom and the P-lone pair, which have to find their positions at the surface of the cages and reduce the number of energetically possible stereoisomers of P x (t-BuC) y R species significantly.…”

“…The differences between 10a and 11a are below 2°for the bond angles and 3 pm for the bond distances outside the PvX bond. The bowl shaped Se 3 -species 12 with its four fused five membered rings, however, has no identified structural relation to the starting cage 5, but its elemental composition points to the ongoing existence of polycyclic P 5 (CR) 4 H species even under harsh chemical conditions. Selenium adds to 5 and rearrangement processes are initiated, leading to one PvSe unit, two P-Se-P bridges and a P-H bond being replaced by a C-H bond.…”