Synthesis of α-phosphono-γ-iodoalkylγ-butyrolactones & vinyl phosphonates

Abstract

Treatment of lithiated homoallylic phosphonates with dimethyl carbamyl chloride gave 2-amidophosphonate derivatives. A solution of 2-amidophosphonate in dimethoxy ethane DME-$H_2O$(2:1 vol) reacted with 2eq. iodine at room temperature to give α-phosphono-γ-iodoalkyl-γ-butyrolactones in good yield. We did not have to isolate the cis-and trans-isomers of α-phosphono-γ-iodoalkyl-γ-butyrolactones, because the stereoisomers afforded same α-methylene-γ-iodoalkyl-γ-substituted-γ-butyrolactone derivatives by Wadsworth-Emmons reaction. But, we have examined the stereoselectivity of cis-and trans-isomers by $^{13}C$ NMR integrals. Despite,trans-isomers are more stable,the stereoselectivity of is not found, the reason of decreased stereoselectivity is the coodination factor of electon pairs of oxygen with partial cationic nitrogen of amide when iodocyclization is occurred. The Treatment of diethyl 1-alkynyl phosphonates with an organocuprates was followed by a quench with saturated ammonium chloride solution (E=H).Mostly, organocuprates attact at the 2-position of 1-alkynylphosphonates vicinally. And 2,2-disustituted vinyl phosphonates could be obtained high yields and stereoselectivity controlled very highly. The geminal difuntionalization of vinyl phosphonates were performed by adding 1-alkynyl phosphonates in THF to cuprates in THF at -78℃. Electrophiles were added dropwise and the reactions allowed to warm to r.t. (1h). Except E= PhSeBr, We could obtain 1,2,2-trisustitued vinyl phosphonates high yields and stereoselectivity.