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

Molecules

Ismail E. Ismailov¹  Ivaylo K. Ivanov¹ 

关键词: phosphorylated α-hydroxyallenes;    electrophilic cyclization;    neighbouring group participation;    2;    5-dihydro-1;    2-oxaphospholes;    (1E)-2;    3-adducts;   

DOI  :  10.3390/molecules190811056

来源: mdpi

【 摘 要 】

This paper discusses a reaction of phosphorylated α-hydroxyallenes with protected or unprotected hydroxy groups involving 5-endo-trig cyclizations. Various electrophilic reagents such as sulfuryl chloride, bromine, benzenesulfenyl and benzeneselenenyl chlorides have been applied. The paper describes the reaction of 1-hydroxyalkyl-1,2-dienephosphonates with electrophiles that produces 2-methoxy-2-oxo-2,5-dihydro-1,2-oxaphospholes due to the participation of the phosphonate neighbouring group in the cyclization. On the other hand, (1E)-alk-1-en-1-yl phosphine oxides were prepared as mixtures with 2,5-dihydro-1,2-oxaphosphol-2-ium halides in a ratio of about 1:2 by chemo-, regio, and stereoselective electrophilic addition to the C²-C³-double bond in the allene moiety and subsequent concurrent attack of the external (halide anion) and internal (phosphine oxide group) nucleophiles. The paper proposes a possible mechanism that involves cyclization and additional reactions of the phosphorylated α-hydroxyallenes.

【 授权许可】

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© 2014 by the authors; licensee MDPI, Basel, Switzerland.