Triphenylphosphine/2,3‐Dichloro‐5,6‐dicyanobenzoquinone (PPh₃/DDQ) System for Conversion of Alcohols and Thiols into Trialkyl Phosphonates

Abstract

An efficient method is reported for the reaction of alcohols or thiols with trialkylphosphitesi nt he presence of aP Ph 3 /2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) mixed reagent system for the preparationo ft rialkyl phosphonate derivatives. The reactions were performed in refluxing acetonitrile to deliver high yields of the title compounds.

Palladium-Catalyzed Solvent-Free Preparation of Arylphosphonates ArP(O)(OAr)2from (ArO)3P via the Michaelis–Arbuzov Rearrangement

“…The Michaelis–Arbuzov reaction, the formation of the P­(V) phosphonates RP­(O)­(OR) 2 by the rearrangement of the P­(III) phosphites via a combination of (RO) 3 P/RX, was discovered more than 120 years ago (Scheme ). , Because the starting materials used in the reaction are cheap and readily available, and also because the reaction process is simple, this reaction has been, ever since, the most famous and frequently used premier synthetic tool for the preparation of phosphonates RP­(O)­(OR) 2 , which have important applications in organic synthesis, flame retardancy, materials chemistry, and biological chemistry . However, the classic Michaelis–Arbuzov rearrangement is essentially restricted to the preparation of aliphatic phosphonates RP­(O)­(OR) 2, as can be seen from its two sequential S N 2 nucleophilic attack mechanisms (Scheme (1)): i.e., the three phosphonates ArP­(O)­(OR) 2 , RP­(O)­(OAr) 2 , and Ar′P­(O)­(OAr) 2 , which have different properties and applications that RP­(O)­(OR) 2 does not have, − could not be similarly prepared.…”

Total Synthesis of Quebrachamine and Kopsiyunnanine D

“…Direct phosphonation of compound 13 using the mixed reagent system of P(OEt) 3 , PPh 3 , and DDQ gave diethyl phosphonate 14. 15 For the preparation of aldehyde (±)-21, as shown in Scheme 3, we selected malononitrile 10 as the starting material. A one-pot sequential alkylation of 10 was conducted by the first addition of the alkylating reagent 11 to afford the monoalkylated intermediate 15, which was directly treated with the ensuing addition of t-BuOK and EtI to deliver the final product 16 with an all-carbon quaternary center in 69% yield.…”

“…Introduction of a benzenesulfonyl group at the N1 position of 9 followed by reduction of the resulting ester 12 with DIBAL-H furnished the corresponding benzyl alcohol 13 in acceptable yields. Direct phosphonation of compound 13 using the mixed reagent system of P­(OEt) 3 , PPh 3 , and DDQ gave diethyl phosphonate 14 …”