Decoded fingerprints of hyperresponsive, expanding product space: polyether cascade cyclizations as tools to elucidate supramolecular catalysis

Abstract

Hyperresponsive XL product space identifies polyether cascade fingerprinting as an attractive tool to elucidate supramolecular catalysis, including pnictogen-bonding, capsule and anion–π catalysts.

Pnictogen‐Bonding Catalysts, Compared to Tetrel‐Bonding Catalysts: More Than Just Weak Lewis Acids

“…This intriguing result calculated for cis,anti ‐ 10 called for experimental validation. The resulting experimental selectivities for cis,anti ‐ 10 were delightfully close to the calculated values not only for Sb(V) 3 , but also for Sb(III) 1 and the complementary Lewis acids [62] …”

“…[54] In the context of this series, their ability to break the Baldwin rules is so far unique, Lewis acids show poor selectivity, Brønsted acids and anion-π catalysts Baldwin selectivity. [62,63] Both B cascades in membranes with 8 and A cascades with 9 thus support that the reactivity accessible from pnictogen-bond catalysis differs from Lewis acid catalysis (Scheme 1). [54,61] However, the chemistry of the tetra-epoxides is too rich to separate and characterize product mixtures.…”

“… [54,61] However, the chemistry of the tetra‐epoxides is too rich to separate and characterize product mixtures. Simple enough to be manageable and still complex enough to be interesting, dimers 10 were envisioned as privileged, hyperresponsive substrates to elucidate supramolecular catalysis systematically [62] . All cyclization products including 11 – 16 have been isolated and characterized, with critical support from X‐ray crystallography.…”

“…In the trans series ( Scheme 3 , top; Table S2 ), AcOH, that is Brønsted acid catalyzed cascade cyclization of 10 was confirmed to afford mostly the BB product 11 ( Scheme 3 , top, red ). Also anion–π catalysts were already known to excel with autocatalysis rather than with breaking of the Baldwin rules [62] . Hydrogen‐bonding catalysts were not considered because previous results gave exceptionally poor activity and mostly Baldwin products [63,81] .…”

“…The alternative trans-(A-HM)-15 from House -Meinwald rearrangement [82 -84] and the respective allylic alcohol 16 form only under special circumstances, that is within molecular capsules. [62] In the cis series (Scheme 3, bottom, Table S1), cyclization into cis-(AB)-13 is allowed because the methyl at the junction is equatorial rather than axial, and thus enriches the product space (Scheme 3, bottom, green). The trends, however, were as in the trans series.…”