Regio- and stereoselective alkyne difunctionalization by using benziodoxole triflate and phosphate ester

• Main Author: Tan, Ploypailin Siew Ling
• Other Authors: Chiba Shunsuke
• Format: Thesis-Master by Research
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Science::Chemistry::Organic chemistry
• Online Access: https://hdl.handle.net/10356/150700
• Institution: Nanyang Technological University

Stereoselective synthesis of tetrasubstituted alkenes has been one of the most challenging subjects in synthetic organic chemistry. Regio- and stereoselective difunctionalization of readily available alkynes represents a conceptually straightforward approach toward this goal. In this Masters study, I have developed such an alkyne difunctionalization reaction using a hypervalent iodine reagent as an electrophile and a phosphate ester as a nucleophile. Thus, a three-component reaction involving an internal alkyne, benziodoxole triflate (BXT), and triethyl phosphate or related phosphate ester proceeds smoothly at room temperature, resulting in trans-addition of the benziodoxole (BX) and phosphate groups. The reaction has proved applicable to a variety of symmetrical and unsymmetrical internal alkynes, thus affording the corresponding β-λ3-iodanyl alkenyl phosphates in a regio- and stereoselective fashion. The BX and phosphate groups of the product can be utilized for sequential cross-coupling, thus allowing for the stereoselective synthesis of all-carbon tetrasubstituted alkenes.