Polycyclic Phosphiranes: Synthesis of C-Substituted BABAR-Phos Compounds

Abstract

BABAR-Phos is a very stable polycyclic phosphirane which is easily synthesized in few steps from dibenzosuberenone. BABAR-Phos is remarkably stable and is not oxygenated with O2 nor does it react with sulfur in boiling toluene. BABAR-Phos can be used as a ligand in homogenous catalysis. Substituents at the carbon of the PC2 heterocycle can be introduced and asymmetric BABAR-Phos were prepared. The coordination chemistry of rhodium complexes containing these as ligands was investigated.

Asymmetric 1,3-dipolar cycloaddition reaction of chiral 1-alkyl-1,2-diphospholes with diphenyldiazomethane

“…26,41,42 Phosphiranes are 3-membered cyclic phosphines with unique stereoelectronic properties, (smaller cone angles and higher inversion barriers compared with their acyclic analogues) and are thought to be poorer s donors and better p acceptors, 40 but their use as ligands in metal-catalyzed reactions is rare. 43 Chiral phosphiranes are especially rare; [44][45][46][47] therefore, the convenient asymmetric cycloaddition reaction reported here is potentially useful for expanding their limited applications in asymmetric catalysis. [48][49][50] In conclusion, we have shown that a diastereoselective 1,3dipolar cycloaddition reaction of 1-alkyl-1,2-diphospholes 1 and 4 with a chiral substituent at phosphorus with diphenyldiazomethane is a new way for the selective synthesis of P-chiral bicyclic phosphiranes from cheap and readily available starting materials.…”

The Dibenzosuberenone Scaffold as a Privileged Substructure: From Synthesis to Application

“…200,201 The C-substituted BABAR-Phos-type ligands and their rhodium(I) complexes were also prepared. 203 New electroluminescent molecular materials are of great interest for organic light-emitting diodes (OLEDs) in flat-panel displays. The Chen group reported new 1:1 hybrid molecules including a 9,9-phenylfluorene framework and functionalized quinoxaline as potentially bipolar, fluorescent chameleons for optoelectronic applications (Scheme 60).…”

Synthesis, Structure, and Reactivity of a Stabilized Phosphiranylium Salt

“…Reaction of Me BABAR-Phos 2 with methyl triflate in toluene (room temperature, 2 h) resulted exclusively in Nalkylation (91 %; d31 P = À83.6 ppm; Scheme 2). The structure of the novel salt 3 was established by X-ray crystal structure determination ( Figure 1) [12] and displays a remarkable long PÀN bond (1.845(1) ) compared with that in the neutral analogues E (1.73-1.74 ) [4a, 13] and phosphiranium ion F (1.628(4) ). [10] DFT calculations at the B3PW91/6-311 + G(d,p) level of theory were performed to understand and compare the electronic structure and reactivity of 2, 3, and the nonobserved P-methylated product F Me .…”

“…Namely, addition of IiPr 2 Me 2 9 resulted in the NHC-stabilized phosphiranylium cation 10 (d31 P = À214.3 ppm). [23,24] The molecular structure of 10, established by X-ray crystal structure analysis (Figure 3), [12] may be viewed as an olefin carbene P I cation. The sum of bond angles at the phosphorus center (S(P): 238.08) is small (cf.…”