Amination and dehydration of 1,3-propanediol by hydrogen transfer: reactions of a bio-renewable platform chemical

Abstract

1,3-propanediol was subjected to a range of amination conditions. The N-heterocyclic carbene piano stool complex [Cp*IrCl 2 (bmim)] was found to be a good catalyst for amination and dehydration in toluene or ionic liquid; product compositions could be tuned by altering the ratio of diol to amine.

Desulfonylation of Tosyl Amides through Catalytic Photoredox Cleavage of NS Bond Under Visible‐Light Irradiation

“…Analysis of the reaction mixture highlighted the side formation of N ‐propyltetrahydroquinoline ( 4 a ); a 61:39 ratio of 3 a / 4 a was reached 16. 24 Modification of the temperature and concentration had only a limited impact on this ratio. Gratifyingly, increasing the amine 1 a /diol 2 a ratio from 1:1.2 to 2:1 minimized the formation of N‐alkylated product 4 a and afforded julolidine 3 a in 72 % yield with a 3 a / 4 a ratio of 87:13 (Table 1, entry 2).…”

Combining bio- and chemo-catalysis for the conversion of bio-renewable alcohols: homogeneous iridium catalysed hydrogen transfer initiated dehydration of 1,3-propanediol to aldehydes

“…When amination is operated in ionic liquid solvents, 10,55 we previously noted 23 that the substrate showed a tendency towards simultaneous dehydration. The resulting aldehydes can react together by aldol condensation and couple to yield C6 products.…”

“…The catalyst 1 and the base are indispensable: in the absence of the iridium catalyst, 1,3-PDO remains unreacted; also, no reaction of 1,3-PDO is observed when the HTID is carried out in the presence of 1 but in the absence of base (In Table 1 10,23 It is also worthy of note that when the HTID of 1,3-PDO was carried out in neat 1, Only a minor effect on the reaction outcome was observed when changing the base:…”

“…This follows the report of amination by hydrogen transfer by coupled bio-and chemo-catalysis, 10,23 and has the additional benefit of easier product separation. By assisting a dehydration reaction, the catalyst and ionic liquid remove oxygen from the bio-alcohol, and this reduces hydrogen bonding, rendering the organic products more volatile and easier to remove from the solvent.…”

“…3,10,23 Of specific interest is the potential of hydrogen transfer and dehydrogenation catalysts to transform bio-renewable alcohols into value added chemicals. 24,25 Reactions that involve the transfer of hydrogen from one organic donor to another (sometimes termed "hydrogen borrowing" reactions) have huge potential in organic synthesis, and have been the subject of several recent reviews.…”