Synthesis and Butyllithium-Induced Cyclisation of 2-Benzyloxyphenylphosphonamidates Giving 2,3-Dihydrobenzo[<i>d</i>][1,3]oxaphospholes

Abstract

A series of fourteen O-ethyl-N-butylphenylphosphonamidates with benzyl ether substituents at the ortho position was prepared and fully characterised. Upon treatment with n-butyllithium in THF at RT, they underwent cyclisation in eight cases to give the novel 2,3-dihydrobenzo[d][1,3]oxaphospholes in moderate to low yield as a single diastereomer, for which the relative configuration was determined by X-ray diffraction in one case.

Keywords

• 1,3-dihydrobenzo[<i>d</i>][1,3]oxaphosphole
• 1,3-benzoxaphosphole
• phosphonamidate
• X-ray structure
• hydrogen bonding