Squaramide‐IRMOF‐16 Analogue for Catalysis of Solvent‐Free, Epoxide Ring‐Opening Tandem and Multicomponent Reactions

Abstract

Tandem and multicomponent one‐pot reactions are highly attractive because they enable synthesis of target molecules in a single reaction vessel. However, they are difficult to control, as they can lead to the formation of many undesired side‐products. Herein we report the use of metal‐organic framework (MOF) pores decorated with organocatalytic squaramide moieties to confine ring‐opening epoxide reactions of diverse substrates. Controlled mono‐addition or tandem reactions inside the pores yield 1,2‐aminoalcohols or 1,2,2′‐aminodialcohols, respectively, in good yields. In addition, this squaramide‐functionalised MOF enables catalysis of higher‐complexity multicomponent reactions such as the catalytic ring‐opening of two different epoxides by a single amine to afford 1,2,2′‐aminodialcohols.

Heterogeneous catalysts with programmable topologies generated by reticulation of organocatalysts into metal-organic frameworks: The case of squaramide

“…4,4'-((3,4-Dioxocyclobut-1-ene-1,2-diyl)bis(azanediyl))dibenzene used as molecular catalyst (MC) was synthesized following a described procedure in Ref. [27].…”

“…1), a wellknown dicarboxylate linker in MOF synthesis [38][39][40]. Once we had designed Sq_tpdc, we synthesized it by a previouslyreported, two-step method [27].…”

“…An alternative, less-explored approach to synthesizing heterogeneous MOF catalysts is to incorporate organocatalytic centers within MOFs [6,7]. This can be done via postsynthetic modifications of the organic linkers in existing MOFs [8][9][10][11][12], or during MOF synthesis, by using organic linkers that contain these organocatalytic centers [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. The latter approach in particular can benefit from reticular chemistry, which can facilitate rational design of MOF-based catalysts with predefined framework topologies and pores.…”

“…Our four-step strategy (Fig. 1) entailed the design and synthesis of the linker, 4,4'-( (3,4-dioxocyclobut-1-ene-1, 2-diyl)bis(azanedyil))dibenzoic acid (Sq_tpdc) [27], which is identical in directionality and length to tpdc but which contains organocatalytic squaramide centers. We evaluated the four MOF-based catalysts for H-bonding catalysis in a representative Friedel-Crafts alkylation and a representative epoxide ring-opening.…”

Stereoselective Multicomponent Reactions in the Synthesis or Transformations of Epoxides and Aziridines

“…The polarity and size of the epoxide substituents directly affected the yield: bulky hydrophobic chains, such as –C 11 H 23 and –C 10 H 21 , required longer reaction times (3–4 days) and provided the products in moderate yields (43 and 56%, respectively). On the other hand, an increase in substituent polarity lead to an increase of both rate and yield, even when bulky groups, such as –CH 2 OTBDMS, were used [36].…”