Synthesis of Secondary Amines by Titanium-Mediated Transfer of Alkenyl Groups from Alcohols

Abstract

Reaction of Ti(NMe2)4 with allyl alcohols and primary amines leads to the selective formation of secondary allylic amines. The allyl transfer from the alcohol to the amine occurs with selective allylic transposition. Due to substituent effects in the reactions, we postulate that the reaction occurs through a [2 + 2]/retro-[2 + 2]-cycloaddition mechanism. It was also found that a similar reaction could be accomplished with homoallylic alcohol. In this case, the more complex mechanism leads to the formation of 1-aza-spiro[5.5]undecane. Possible pathways for the homoallylic transfer and cyclization are discussed.

Oxovanadium(V)‐Catalyzed Direct Amination of Allyl Alcohols

“…The activation of amines by oxovanadium(V) compounds is considered to be a convenient strategy for catalytic transformation of amines. Direct amination of allyl alcohols has been demonstrated by using in situ‐ generated (imido)titanium compounds through [3,3]‐sigmatropic rearrangement . This process, however, requires a stoichiometric amount of titanium compounds and excess amount of amines.…”

“…Direct amination of allyl alcohols has been demonstrated by using in situgenerated (imido)titanium compounds through [3,3]-sigmatropic rearrangement. [10] This process, however, requires a stoichiometric amount of titanium compounds and excess amount of amines. To the best of our knowledge, oxovanadium (V) compounds have never been utilized as a catalyst for direct amination of allyl alcohols.…”

Hydroaminoalkylation: Early-Transition-Metal-Catalyzed α-Alkylation of Amines

“…In 2006, Odom observed α-alkylation adjacent to nitrogen during the investigation of a stoichiometric titaniummediated transfer of alkenyl groups from alcohols to primary amines (Scheme 6). 13 In one example, the reaction of Ti(NMe 2 ) 4 with homoallylic alcohol and cyclohexylamine gave 1-azaspiro [5.5]undecane, demonstrating that titanium is capable of mediating C-C bond formation adjacent to nitrogen.…”

The Progression of Synthetic Strategies to Assemble Titanium Complexes Bearing the Terminal Imide Group

“…[3][4][5][6][7] For example, this type of functionality is responsible for fundamentally important reactions such as the intermolecular activation of aliphatic (including methane) [8,9] as well as aromatic C À H bonds. [7,[10][11][12][13] The ubiquitous imide group can also participate in other processes such as cycloaddition reactions with substrates like carbon dioxide, [14][15][16][17][18][19][20][21] carbon disulfide, [14-16, 19, 22] ke-tones, [16,22,23] alkenes (intra-and intermolecularly), [24,25] A C H T U N G T R E N N U N G alkynes, [22,[24][25][26] nitriles, [23,27] isonitriles, [16,28] imines, [16,23,29,30] carbodiimides, [4,16,[30][31][32] allenes, [4,24,33] allylic alcohols, [34] and carboxamides…”

“…For example, this type of functionality is responsible for fundamentally important reactions such as the intermolecular activation of aliphatic (including methane)8, 9 as well as aromatic CH bonds 7. 10–13 The ubiquitous imide group can also participate in other processes such as cycloaddition reactions with substrates like carbon dioxide,14–21 carbon disulfide,14–16, 19, 22 ketones,16, 22, 23 alkenes (intra‐ and intermolecularly),24, 25 alkynes,22, 24–26 nitriles,23, 27 isonitriles,16, 28 imines,16, 23, 29, 30 carbodiimides,4, 16, 30–32 allenes,4, 24, 33 allylic alcohols,34 and carboxamides35 along with several other polar reagents 4–7. Depending on the complex, incomplete or complete metathetical reactions can often take place (even catalytically) with these types of substrates, thus leading to Wittig‐like chemistry and extrusion of organic products in which the imide group has been swiftly incorporated.…”