[P(MeNCH₂CH₂) ₃N], ein effizienter Katalysator für die Umwandlung von Isocyanaten in Isocyanurate

Abstract

Auf die ungewöhnlich starke Lewis‐Basizität des P‐Atoms und auf die Fähigkeit zu unterschiedlich starken transanularen P‐N‐Wechselwirkungen ist die hohe katalytische Aktivität von [P(MeNCH2CH2) 3N] in der Titelreaktion zurückzuführen. So bildet sich, wie rechts angedeutet, in 3 min Triphenylisocyanurat (Ar = C6H5) in 97% Ausbeute und in 8 min Tri‐para‐methoxyphenylisocyanurat (Ar = 4‐MeOC6H4) in 99% Ausbeute.

Fluoride-Catalyzed Reduction of Palladium(II) to Palladium(0)−Phosphine Complexes

“…Recently we have been exploring the application of pro-azaphosphatrane 1 , first reported from our laboratories, − as a superior nonionic base in the synthesis of acylated alcohols, porphyrins, α-C-acylamino acids, trans olefins, , chiral auxiliary-bearing isocyanides, mono-alkylated β-dicarbonyls, and as an efficient catalyst for the trimerization of isocyanates and the protective silylation of alcohols . The very stable conjugate acid 2 of commercially available 1 has a p K a (41 in MeCN 17 ) which is about 17 units larger than the conjugate acid of DBU, a strong nonnucleophilic base widely used in synthetic applications.…”

Synthesis, Characterizations and Applications of Fluoroazaphosphatranes

“…Compared to phosphazenes, their protonation occurs on the phosphorus atom leading to the formation of highly stable azaphosphatranes. [2] Verkade's superbases have found numerous applications from basic and nucleophilic catalysts or stoechiometric reagents, [3] ligands for transition metals, [4] to Lewis bases in frustrated Lewis pair (FLP) systems. [5] Moreover, their confinement in molecular cavities strongly affects the thermodynamics and kinetics of the proton transfer and leads to supramolecular catalysts displaying improved catalytic activities or selectivities.…”

Azaphosphatranes Catalyzed Strecker Reaction in the Presence of Water

“…Azaphosphatranes are the protonated counterparts of the proazaphosphatranes (Verkade's superbases) described by J. G. Verkade in 1989 (Figure 1). [1] In contrast to proazaphosphatranes, which have been widely studied in organic transformations as non-ionic bases or organocatalysts, [2,3] and also as ligands in metal-catalyzed reactions, [4] their protonated analogues have attracted much less interest. In 1999, the Verkade group first used azaphosphatranes as procatalysts in dehydrohalogenations and debrominations in the presence of sodium hydride.…”