Bifunctionalized Allenes, Part XI: Competitive Electrophilic Cyclization and Addition Reactions of 4‐Phosphorylated Allenecarboxylates

Abstract

The reaction of the 4‐phosphorylated allenecarboxylates with different electrophilic reagents such as sulfuryl chloride, bromine, benzenesulfanyl, and benzeneselanyl chlorides takes place with a 5‐endo‐trig cyclization or 2,3‐addition reaction depending on the kind of the substituents in the phosphoryl group. Treatment of the 4‐(dimethoxyphosphopyl)‐allenoates with electrophiles gives a mixture of 2,5‐dihydro‐1,2‐oxaphospholes and furan‐2(5H)‐ones in the ratio of about 1.7:1 as a result of the neighboring group participation of phosphonate and carboxylate groups in the cyclization. On the other hand, (3E)‐4‐(diphenylphosphoryl)‐alk‐3‐enoates were prepared, in moderate yields, by chemo‐, regio, and stereoselective electrophilic addition to the C2C3‐double bond in the allenoate moiety. A possible mechanism involving cyclization and addition reactions of the 4‐phosphorylated allenecarboxylates was proposed.

Bifunctionalized Allenes. Part XV. Synthesis of 2,5-dihydro-1,2-oxaphospholes by Electrophilic Cyclization Reaction of Phosphorylated α-Hydroxyallenes

“…A rationale for this reaction based on available literature data [13,14,15,16,17,18,19,20,21,22,23] and on our recent results [51,52,53,54] is depicted in Scheme 5.…”

“…Our long-standing research program focuses on the development of efficient electrophilic cyclization reactions of 1,3-bifunctionalized allenes [53,54]. More specifically, our attention is drawn to 1,1-bifunctionalized allenes such as 1 – 4 that comprise a phosphoryl and a hydroxyalkyl group (Scheme 1).…”

Fifty Years of (Benz)oxaphospholene Chemistry

“…[72] Competitive reactionsa lso occurred when the phosphonyl group is in g-position with respectt ot he carboxyl function. [73] Treatment of 1-phosphoryl-1-sulfinate-2,3-butadiene 89 b similarly yielded am ixture of two heterocycles, which could each be isolateds eparately. [74] Alternatively, phosphono pentadienes can serve as precursors for the electrophile-induced synthesis of oxaphospholenes as well.…”

“…Both the oxaphospholene 90 , which was formed as the major product, and the lactone 91 were isolated . Competitive reactions also occurred when the phosphonyl group is in γ‐position with respect to the carboxyl function . Treatment of 1‐phosphoryl‐1‐sulfinate‐2,3‐butadiene 89 b similarly yielded a mixture of two heterocycles, which could each be isolated separately …”

Bifunctionalized Allenes. Part XVI. Synthesis of 3-Phosphoryl-2,5-dihydrofurans by Coinage Metal-Catalyzed Cyclo-isomerization of Phosphorylated α-Hydroxyallenes

“…Our long-standing research program focuses on the development of efficient cyclization reactions of 1,1- [ 50 , 51 ] and 1,3-bifunctionalized allenes [ 52 , 53 ]. More specifically, our attention is drawn to phosphorylated hydroxyallenes as 1,1-bifunctionalized allenes that comprise a phosphoryl and a hydroxyalkyl group.…”