Hydromagnesiation of 1,3‐Enynes by Magnesium Hydride for Synthesis of Tri‐ and Tetra‐substituted Allenes

Abstract

A protocol for regio-controlled hydromagnesiation of 1,3-enynes was developed using magnesium hydride that is generated in situ by solvothermal treatment of sodium hydride (NaH) and magnesium iodide (MgI 2) in THF. The resulting allenylmagnesium species could be converted into tri-and tetra-substituted allenes by subsequent treatment with various carbon-and silicon-based electrophiles with the aid of CuCN as a catalyst.

Deciphering the Chameleonic Chemistry of Allenols: Breaking the Taboo of a Onetime Esoteric Functionality

“…More particular transformations to yield the allenol motif include the synthesis of exocyclic allenols through carbocyclization of both allenynes, 99 or carbonyl enynes, 100 , 101 the deoxygenation of pentadiyn diols, 102 the aza-Cope-type rearrangement of propargyl indoles, 103 one example of ethynylation and S N 2′ reaction, 104 or transformations from 1,3-enynes, such as alkylarylations, 105 or hydromagnesiation. 106 …”

Generation of organo-alkaline earth metal complexes from non-polar unsaturated molecules and their synthetic applications

“…The unique hydridic reactivity of magnesium hydride (44) generated in situ from sodium hydride (42) and magnesium iodide (43) was extended further to regioselective hydromagnesiation of 1,3-enynes 56 to form an equilibrium mixture of allenylmagnesium 57 and propargylmagnesium 58 (Scheme 12). 35 Downstream functionalization of the resulting organomagnesium intermediates 57 and 58 was demonstrated by subsequent treatment with a series of alkyl and silyl halides in the presence of CuCN as a catalyst, affording polysubstituted allenes 59-62.…”

Iron-Catalyzed Regio- and Stereoselective Hydrosilylation of 1,3-Enynes To Access 1,3-Dienylsilanes

“…However, such transformation encounters considerable difficulties to control regio- and stereoselectivity due to the existence of several competing pathways including 1,2-, 1,4-, or 3,4-hydrosilyation, as well as other side reactions (eq ). …”