Palladium-Catalyzed Propargylic Substitution with Phosphorus Nucleophiles: Efficient, Stereoselective Synthesis of Allenylphosphonates and Related Compounds

Abstract

A new, efficient method is developed, based on a palladium(0)-catalyzed reaction of propargylic derivatives with various phosphorus nucleophiles, to produce allenylphosphonates and their analogues with defined stereochemistry in the allenic and the phosphonate moiety.

[3,3]‐Sigmatropic Rearrangement/Allylboration/Cyclization Sequence: Enantioenriched Seven‐Membered‐Ring Carbamates and Ring Contraction to Pyrrolidines

“…[2] Several approaches are available for their synthesis,a nd the most common ones are based on intramolecular cyclization of 1,4-aminoalcohols or derivatives. [6,7] Dehydration with phosphine and carbon tetrabromide in the presence of triethylamine, [5d] followed by direct addition of aldehydes to the crude reaction mixture,a nd then aqueous NaHCO 3 15 hours later, afforded the cyclic ene carbamates 5 in good to moderate yields (threestep process;T able 1). [4] Our interest in the use of boronic esters in cascade reactions [5] led us to consider their utility for the synthesis of enantioenriched 4,5-dihydro-1,3-oxazepin-2ones.T hese versatile intermediates led, through an unprecedented ring contraction reaction, to tetrasubstituted pyrrolidines,another family of major biological significance.…”

“…[6,7] Dehydration with phosphine and carbon tetrabromide in the presence of triethylamine, [5d] followed by direct addition of aldehydes to the crude reaction mixture,a nd then aqueous NaHCO 3 15 hours later, afforded the cyclic ene carbamates 5 in good to moderate yields (threestep process;T able 1). [6,7] Dehydration with phosphine and carbon tetrabromide in the presence of triethylamine, [5d] followed by direct addition of aldehydes to the crude reaction mixture,a nd then aqueous NaHCO 3 15 hours later, afforded the cyclic ene carbamates 5 in good to moderate yields (threestep process;T able 1).…”

Recent Advances in H-Phosphonate Chemistry. Part 2. Synthesis of C-Phosphonate Derivatives

“…However, a Scheme 18 Pyridine-directed palladium catalyzed phosphonylation of C(sp novel synthetic method was developed for the preparation of allenylphosphonates, applicable to biologically important natural product derivatives [129,130]. The method shown in Scheme 19 is based on a palladium-catalyzed propargylic substitution with phosphorus nucleophiles, and represents a new means of formation of the P-C bond.…”

“…The first catalytic procedure for Cu(I)-mediated coupling of aryl halides with H-phosphonate diesters, based on the Ullmann-type of chemistry, was described in 2003 by Buchwald [129,130] et al [132]. Since then, the number of applications of copper as a catalyst has steadily increased [133][134][135].…”

New and Efficient Synthesis of 1,3-Dienylphosphonates by Palladium-Catalyzed Substitution of Propargylic Esters to Diethyl Phosphite

“…However, the catalyst was less efficient and high catalyst loading was required (10-20 mol%). Recently, Kalek et al [15] reported the Pd-catalyzed propargylic substitution with phosphorus nucleophiles to the synthesis of allenylphosphonates [Scheme 1, Eq. (2)].…”