Calcium‐Catalyzed Direct Amination of π‐Activated Alcohols

Abstract

A calcium-catalyzed direct amination of pactivated alcohols with different nitrogen nucleophiles under very mild reaction conditions is presented. The high reactivity of the calcium catalyst allows for an efficient conversion of secondary and tertiary benzylic and allylic as well as tertiary propargylic alcohols. Nitrogen nucleophiles such as carbamates, tosylamides and anilines are readily alkylated at room temperature.

Calcium‐Catalyzed Direct Coupling of Alcohols with Organosilanes

“…In an earlier publication, we already discussed the role of the additive as a precursor for the formation of the catalytic species by anion exchange. [6] Unfortunately, the formation of the catalytically active CaNTf 2 BF 4 species proved less efficient under the reaction conditions starting from commercially available Ca(BF 4 ) 2 and Bu 4 NNTf 2 (Table 1, Entry 7). As for previously described calcium-catalyzed reactions, dichloromethane proved to be the most suitable solvent for the allylation of alcohols.…”

“…The transformation is incomplete and stops after the intermediary formation of ether 3c in stronger coordinating, ethereal solvents (Table 1, Entries 8 and 9). [6] The reaction in toluene, giving only slightly poorer results than those obtained in dichloromethane, represents a potential alternative (Table 1, Entry 10) where non-halogenated solvents are mandatory. To explore the generality and scope of the reaction, a series of different alcohols was allylated under the optimized reaction conditions ( Table 2).…”

Direct Amination of Alcohols Catalyzed by Aluminum Triflate: An Experimental and Computational Study

“…Among the best performing catalysts, triflates and triflimides stand out as Lewis superacids. [9] Metal triflates and triflimides, based on Ca, [10] Al, [11] In, [12] Yb, [13] La, [13c] Hf, [13c] Bi, [14] Cu, [15] Ag, [16] Hg, [17] and Au, [18] including the parent triflic acid (HOTf), [19] were found active for a broad range of acid-catalyzed reactions. In particular, Mashima and coworkers reported Al(OTf)3 as a powerful catalyst for the amination of secondary allylic or benzylic alcohols.…”

“…Due to their polar nature, solvents typically used for SN1-type reactions, such as dichloromethane, [10] dioxane, [14b, 19] nitromethane, [11b, 13a, 16b] and water, [12, 14a] can stabilize ionic intermediates. Additives such as KPF6 for Bi(OTf)3 [14b] and Bu4NPF6 for Ca(NTf2)2 [10] can enhance the catalytic performance, most likely by generating more active species by exchange of TfO -and NTf2 -anions for PF6 -.…”

Alcohols in direct carbon-carbon and carbon-heteroatom bond-forming reactions: recent advances

“…126 Amination of alcohols [127][128][129][130][131][132][133] in the presence of Lewis acid as a catalyst has been reviewed; 134 selected results are shown in Table 17. For the amination of allylic alcohols Pd(Xantphos)Cl 2 , was used as the catalyst.…”