Unique chemoselective Strecker-type reaction of acetals with TMSCN catalyzed by MgI₂ etherate

Design and construction of polyaromatic group containing Cd(ii)-based coordination polymers for solvent-free Strecker-type cyanation of acetals

“…A similar type of phenomenon was also reported. 26,27 However, for 3-bromo benzaldehyde diethyl acetal, only 65 or 55% yield of the final product was achieved (entry 4, Table 2) under the indicated reaction conditions, showing a lower reactivity of the CH(OEt) 2 group compared to that of CH(OMe) 2 , at the acetal.…”

“…, for a higher reaction time although at a lower temperature than ours. 26 Moreover, the use of tetracyanoethylene (as catalyst) and TMSCN produced 72% yield after 5 h of reflux (entry 5, Table 3). 37 By using BiBr 3 (1 mol%) as catalyst, 89% of final product yield was achieved within 1 h of reaction time (entry 4, Table 3).…”

“…A proposed catalytic cycle for the cynation of acetal catalyzed by CP 1 or 2 , based on reported proposals, 26,27 is presented in Scheme 3. Firstly, the acetal is activated by a dinuclear Cd( ii ) centre to give an oxocarbenium cation species.…”

“…A similar type of reaction mechanism can also be observed for the cyantion of acetals by TMSCN and with MgI 2 etherate as the catalyst. 26 For such a case the acetal is activated by the mild Lewis acidic MgI 2 etherate forming the oxocarbenium cation followed by the transfer of CN − group from TMSCN to generate the cyanated product upon evolution of TMSOMe.…”

“…, 3-amino-2-alkenenitriles, α-alkoxyketones, etc. 19 The synthesis of α-alkoxynitriles, through cyanation of acetals with trimethylsilyl cyanide (TMSCN) in the presence of different Lewis acids, such as BiBr 3 , 20 [Rh(COD)Cl] 2 , 21 SnCl 2 , 22 TiCl 4 , 23 ZnI 2 , 24 BF 3 ·Et 2 O 25 and MgI 2 etherate, 26 has been reported. Other cyanating agents, such as cyanoamine in the presence of trichlorosilyl triflate, have also been used to catalyze cyanation of acetals and orthoesters.…”