Dual supermesityl stabilization: 1-Alkyl-1H-[1,2,4]triphospholes, with among the most planar and least sterically hindered sigma(3),lambda(3)-phosphorus atoms, and novel C2P3S4 folded heterocycles

作者：Ionkin Alex S^*; Marshall William J; Fish Brian M; Marchione Alexander A; Howe Laurie A; Davidson Fredric; McEwen Charles N

来源：Organometallics, 2008, 27(19): 5118-5121.

DOI：10.1021/om800528g

1-Methyl-3,5-bis(2,4,6-tri-tert-butylphenyl)-1H-[1,2,4]triphosphole (6) and 1-benzyl-3,5-bis(2,4,6-tritert-butylphenyl)-1H-[1,2,4]triphosphole (7) were synthesized and isolated with among the most planar and least sterically hindered sigma(3),lambda(3)-phosphorus atoms, which are an indication of the aromaticity of this heterocycle. The sums of the bond angles at the sigma(3),lambda(3)-phosphorus atoms in 6 and 7 are close to 360 degrees. sigma(3),lambda(3)-Phosphorus atoms in 6 and 7 have substantial deshielded chemical shifts at 151.86 and 161.71 ppm in the P-31 NMR spectra. The parental trimethylphosphine and tribenzylphosphine with pyramidal phosphorus atoms have chemicals shifts at -62.0 and -10.4 ppm. There are large P-P coupling constants: (1)J(PP) = 549.7 Hz for 6 and 553.3 Hz for 7. This is further evidence of a significant delocalization of the electron density in these polyphosphorus heterocycles. Compound 7 reacts with sulfur to afford 3-benzyl-2,4-bis(2,4,6-tri-tert-butylphenyl)-6,7-dithia- 1,3 lambda(5),5-triphosphabicyclo[3.1.1]hepta-2,3-diene 1,5-disulfide (8), which is the first example of a C2P3S4 folded heterocycle. The formation of 8 involves an unusual 1,3-benzyl shift with oxidation of all lambda(3)-phosphorus atoms to lambda(5)-phosphorus atoms.

• 出版日期2008-10-13