215854-31-2Relevant academic research and scientific papers
Functionalized ether derivatives of HOCH2C(CH2PPh2)3 and related tripod ligands - Synthesis and coordination chemistry
Schober, Peter,Soltek, Rainer,Huttner, Gottfried,Zsolnai, Laszlo,Heinze, Katja
, p. 1407 - 1415 (2008/10/08)
Neopentane-derived tripod ligands of the general type HOCH2C(CH2PPh2)(CH2Y)(CH 2Z) (1; Y, Z = PPh2, SR) are notoriously resistant to ether formation at their hydroxy group. Two routes have been found, which allow the transformation of 1 into ether functionalized tripod ligands ROCH2C(CH2PPh2)(CH2Y)(CH 2Z) (Y = Z = PPh2: 5, Y = Z = SR: 8). One of these strategies relies upon the ?3 coordination of 1 in 1·Mo(CO)3 (2). By this way the donor groups are efficiently protected and the steric encumbrance of the CH2OH group at the backbone of the ligands is greatly reduced by fixing three arms of the neopentane scaffolding to the metal center. After deprotonation, reaction with electrophiles will produce the corresponding ether derivatives ROCH2C(CH2PPh2)(CH2Z)2 (3). Mesylation of 2 leads to MeSO2OCH2C(CH2PPh 2)3·Mo(CO)3 (4), which reacts with alkoxides to produce 3 in a sequence of reversed polarity. Ligands 5 [ROCH2C(CH2PPh2)3] are liberated from 3 by UV irridation of their solutions in the presence of pyridine N-oxide. Direct etherification of 1 is also possible in some cases after deprotonation of 1 by KOfBu and subsequent reaction with an electrophile RX in the narrow temperature range between -10 and +20 °C. By this way, ω-methyl polyglycol ether functions are easily introduced resulting in H3C(OC2H4)nOCH2C(CH 2PPh2)3 (5g, h).
