Triphenylphosphine-Catalyzed Synthesis of Stable, Functionalized 2H-Oxetes

Synthesis and Reactions of Stabilized Phosphorus Ylides

“…The reaction between (1) and (2) in the presence of arylsulfonyl isocyanates (167) lead to dialkyl 2,5-dihydro-5-oxo-1,2-azaphosphole-3,4-dicarboxylates (168). On the basis of the well-established chemistry of trivalent phosphorus nucleophiles, it is reasonable to propose that azaphosphole (168) results from the initial addition of (1) to the acetylenic ester (2) and subsequent attack of the resulting zwitterionic intermediate (3) on the carbonyl carbon of the arylsulfonyl isocyanate (167) to yield betaine (169), which apparently cyclizes, under the reaction conditions employed, to produce the azaphosphole (168) (Scheme 45) [172].…”

“…On the basis of the known chemistry of trivalent phosphorus nucleophiles, it is reasonable to assume that 2H-oxetes (148) result from an initial addition of (1) to (2) and followed by addition to the carbonyl group of -haloketones (147). The negatively charged oxygen atom attacks on an electron-deficient olefinic carbon atom to produce the oxetane salt (150) and subsequent loss of TPP gives the stable functionalized 2H-oxete (148) (Scheme 40) [168]. 4,5-Dialkyl 1-isopropyl 3-isopropoxy-1H-pyrazole-1,4,5-tricarboxylate (152) was obtained in excellent yield from the reaction of (2) and diisopropyl azodicarboxylate (151) in the presence of (1) in dry dichloromethane.…”

1H NMR Kinetic Investigation of the Equilibrium between the Z- and E-Isomers in a Stable Phosphorus Ylide Involving 2-Mercaptobenzimidazole

“…Developments of new protocols for the synthesis of physiologically active compound have not been possible without phosphorus ylides. These compounds have attained great significance as widely used reagents for linking synthetic building blocks with the formation of carbon-carbon double bonds and the development of new routes to heterocyclic systems [5,6]. Consequently much interest has been given to the study of the synthesis, structure and properties of P-ylides and their derivatives [7].…”

Synthesis of Halogenated α,β‐Unsaturated γ‐Butyrolactone Derivatives by Triphenylphosphine‐Catalyzed Cyclization of α‐Halogeno Ketones with Dialkyl Acetylenedicarboxylates (=Dialkyl But‐2‐ynedioates)

“…The presence of electron-withdrawing groups such as halogen atoms at the a-position of the ketones was necessary in this reaction. We reported the reaction of 1,1dichloroacetone (¼ 1,1-dichloropropan-2-one) and phenacyl chloride (¼ 2-chloro-1phenylethanone) as electron-deficient ketones with acetylenic esters in the presence of Ph 3 P [12]. Dihalogeno ketones similarly afforded the expected g-butyrolactone derivatives in high yields.…”

“…Cyclization of a-chloro ketones resulted in higher yields than that of the corresponding a-bromo ketones. 95 (2012) 810 2012 Verlag Helvetica Chimica Acta AG, Zürich a ) Yield of isolated product 4. b ) Reported previously [12]. -Several methods have been reported for the synthesis of a,bunsaturated g-butyrolactones [1 -10].…”