Hydromagnesiation of 1,3-enynes and 1,3-dienes by magnesium hydride

• Main Author: Li, Yihang
• Other Authors: Chiba Shunsuke
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Science::Chemistry::Organic chemistry
• Online Access: https://hdl.handle.net/10356/172239
• Institution: Nanyang Technological University

Organomagnesium reagents are one of the most versatile organometallics in synthetic chemistry. This thesis describes the hydromagnesiation of 1,3-enynes and 1,3-dienes with magnesium hydride generated by solvothermal treatment of sodium hydride and magnesium iodide, affording organomagnesium intermediates. The downstream functionalization with electrophiles affords various functional molecules. Chapter 1 provides a general overview of the functionalization and preparation of organomagnesium reagents. Chapter 2 describes a novel protocol for the synthesis of tri- and tetra-substituted allenes via the hydromagnesiation of 1,3-enynes and the regioselective downstream functionalization with electrophiles in the presence of the copper catalyst. The solvothermal treatment of sodium hydride and magnesium iodide can generate active magnesium hydrides, forming the equilibrium of propargylmagnesium and allenylmagnesium intermediate. Chapter 3 introduces the treatment of the equilibrium of allenylmagnesium and propargylmagnesium with nitro compounds in the presence of triethylamine after the hydromagnesiation of 1,3-enynes with sodium hydride and magnesium iodide, affording the synthetically useful nitrones. Chapter 4 introduces the reactivity of the in-situ generated magnesium hydrides via the counterion metathesis towards 2-aryl-1,3-dienes. The resulting allylmagnesium intermediate performs regioselective functionalization with different electrophiles. Chapter 5 presents the experimental data for the respective chapter 2, 3, and 4.