Efficient and Controllable Esterification of P(O)‐OH Compounds Using Uronium‐Based Salts

Abstract

An efficient and convenient method is developed for the direct esterification of P(O)-OH compounds with alcohols under room temperature. The protocol makes use of inexpensive uroniumbased salts as coupling reagents and shows good tolerance towards numerous alcohols, giving the corresponding esterification products in good to excellent yield. Phenols are also tolerated in this reaction. It is a simple way to produce a broad spectrum of functionalized phosphinates, phosphonates, and phosphates from basic P(O)-OH starting materials.

Highly Efficient and Convenient Access to Phosphinates via CHCl3‐Assisted Direct Phosphorylation between R2P(O)H and ROH by Phosphonium Salt Catalysis

“…As they are also widely present in pharmaceuticals and other valuable organic materials Accordingly, much attention has been dedicated to P–O bond formation for the construction of phosphinate compounds. Over the past decades, several typical routes reported relied on the addition of alcohols to sensitive phosphinic chlorides [R 2 P(O)Cl], or on the esterification of phosphinic acids [R 2 P(O)OH], including via the CCl 4 ‐mediated Atherton‐Todd process . In view of the need for more environmentally‐friendly and atom‐economical organic reactions, developing greener syntheses of phosphinate derivatives remains a highly desirable, albeit challenging task …”

“…Meanwhile, the metal‐free systems including Tf 2 O/H 2 O 2 and Ph 2 I + could also promote this transformation, yielding corresponding phosphinate products ,. [3b] Moreover, the C–H activation/phosphorylation and other related strategies were disclosed as efficient ways as well. Of note, among all reported approaches so far, either metal catalyst or oxidant was essential for the reactivity.…”

P-Chloride-Free Synthesis of Phosphoric Esters: Microwave-Assisted Esterification of Alkyl- and Dialkyl Phosphoric Ester-Acids Obtained from Phosphorus Pentoxide

“…29 The esterification of P-acids, especially that of phosphinic acids, is a hot topic. Xiong and Tang together with co-workers elaborated the esterification of phosphinic acids applying coupling agents, such as N,N′-carbonyl diimidazole 30,31 or uronium-based salts, 30,32 or using cyclic diaryliodonium salts as the reactant, leading to diphenylation. 33 Our group has experience in the microwave (MW)-assisted direct esterification of P-acids.…”

Rapid Mechanochemical Synthesis of Amides with Uronium-Based Coupling Reagents, a Method for Hexa-amidation of Biotin[6]uril

“…The acyl phosphate pathway probably contributes less in the case of the more reactive TCFH reagent, which also produced a rather low 30% yield of 17 (Figure 2). The exact mechanistic sequence leading to acyl phosphates C from COMU, RCO2H and K2HPO4 remains unclear but may include the reaction of acyl uronium intermediate A with HPO4 2anion (Scheme 4) or, alternatively, the initial formation of uronium phosphate 71 by the reaction of COMU with K2HPO4.…”