Highly Selective Synthesis of [(Z)-3-Chloro-2-(phenylselanyl)-1-alkenyl]phosphonates and 2-Ethoxy-4-(phenylselanyl)-2,5-dihydro-1,2-oxaphosphole 2-Oxides by Electrophilic Reaction of 1,2-Alkadienylphosphonates with PhSeCl

• Published in: European Journal of Organic Chemistry 2010-01, Vol.2010 (1), p.101-110
• Main Authors: He, Guangke, Yu, Yihua, Fu, Chunling, Ma, Shengming
• Format: Article
• Language: English
• Subjects: Aliphatic compounds; Allenes; Chemistry; Cyclization; Electrophilic addition; Exact sciences and technology; Heterocyclic compounds; Miscellaneous; Organic chemistry; Organometalloidal and organometallic compounds; P derivatives; Phosphorus; Preparations and properties; Selenium
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.200900913

The reactions of monosubstituted 1,2‐alkadienylphosphonates with PhSeCl in THF or dioxane/H2O (10:1) at 70 °C afforded the selenochlorination products [(Z)‐3‐chloro‐2‐(phenylselanyl)‐1‐alkenyl]phosphonates with very high chemo‐ and stereoselectivity, whereas the same reaction with di‐ and trisubstituted allenylphosphonates afforded 2‐ethoxy‐4‐(phenylselanyl)‐2,5‐dihydro‐1,2‐oxaphosphole 2‐oxides exclusively. It was interesting to note that the stereoselctivity for the selenochlorination reaction is opposite to that of the iodo‐ and selenohydroxylation reactions of (allenyl)diphenylphosphane oxides with Cl– acting as the nucleophile. The stereoselectivity of the cyclization reaction is clearly different from that of the selenochlorination reaction. The reactions of monosubstituted 1,2‐alkadienylphosphonates with PhSeCl in THF or dioxane/H2O (10:1) afforded [(Z)‐3‐chloro‐2‐(phenylselanyl)‐1‐alkenyl]phosphonates with a very high (Z) stereoselectivity, whereas the same reaction with di‐ and trisubstituted allenylphosphonates afforded 2‐ethoxy‐4‐(phenylselanyl)‐2,5‐dihydro‐1,2‐oxaphosphole 2‐oxides exclusively.