DOI: 10.14469/hpc/3943 Metadata

Created: 2018-03-23 10:02

Last modified: 2020-01-25 15:15

Author: Henry Rzepa

License: Creative Commons: Public Domain Dedication 1.0

Funding: (none given)

Co-author: Alan Spivey
Co-author: Christian Nielsen
Co-author: David Sale
Co-author: Jordi Bures
Co-author: Wouter Mooij

Description

Herein we report a combined experimental and computational investigation of the acid catalysed cyclocondensation reaction between styrenyl homoallylic alchohols and salicycaldehdyes to form furanochromanes. We disclose a previously unreported isomerisation of the ‘unnatural’ trans-fused products to the diastereomeric ‘natural’ cis-fused congeners. Notwithstanding the appeal of assuming this corresponds to endo to exo isomerisation of Diels-Alder (D-A) adducts via concerted retro-cycloaddition/cycloaddition reactions of an in situ generated ortho-quinone methide with the styrenyl alkene, our combined Hammett/DFT study reveals a stepwise Prins-like process via discrete benzylic carbocation intermediates for all but the most electron deficient styrenes. As these reactions fortuitously lie at the intersection of these two mechanistic manifolds, it allows us to propose an experimentally determined indicative + value of ca. -3 as marking this nexus between a stepwise Prins-type pathway and a concerted cycloaddition reaction. This value should prove useful for categorising other reactions formally involving ‘ortho-quinomethides’, without the need for the extensive computation performed here. Logical optimisation of the reaction based upon the mechanistic insight led to the use of HFIP as an additive which enables exclusive formation of ‘natural’ cis-fused products with a ~100-fold reaction rate increase and improved scope

Members

DOI	Description
10.14469/hpc/4137	FAIR data for (E)-6-((((E)-4-(4-methylphenyl)but-3-en-1-yl)oxy)methylene)cyclohexa-2,4-dien-1-one
10.14469/hpc/4101	FAIR data for (E)-6-((((E)-4-(4-nitrophenyl)but-3-en-1-yl)oxy)methylene)cyclohexa-2,4-dien-1-one
10.14469/hpc/4102	FAIR data for (E)-6-((((E)-4-(4-aminophenyl)but-3-en-1-yl)oxy)methylene)cyclohexa-2,4-dien-1-one
10.14469/hpc/4175	FAIR Table. Calculated transition state properties, B3LYP+GD3BJ/Def2-TZVPP/SCRF=ethanol
10.14469/hpc/4151	(E)-4-(4-(tert-butyl)phenyl)but-3-en-1-ol
10.14469/hpc/4149	Racemate of (3aR,4S,9bR)-4-(p-tolyl)-2,3,3a,4,5,9b-hexahydrofuro[3,2-c]quinoline
10.14469/hpc/4513	Calculated kinetic isotope effects for acid Catalyzed Furanochromane Formation
10.14469/hpc/4068	FAIR data for Acid Catalyzed Furanochromane Formation – Stepwise via an Oxonium Prins Reaction or Concerted via a Hetero Diels Alder Reaction? HCl catalyzed cis stereochemistry
10.14469/hpc/3985	FAIR data for Acid Catalyzed Furanochromane Formation – Stepwise via an Oxonium Prins Reaction or Concerted via a Hetero Diels Alder Reaction? HCl catalyzed trans stereochemistry
10.14469/hpc/3984	FAIR data for Acid Catalyzed Furanochromane Formation – Stepwise via an Oxonium Prins Reaction or Concerted via a Hetero Diels Alder Reaction? Uncatalyzed, trans stereochemistry
10.14469/hpc/4098	FAIR data for (E)-6-((((E)-4-(4-chlorophenyl)but-3-en-1-yl)oxy)methylene)cyclohexa-2,4-dien-1-one
10.14469/hpc/4099	FAIR data for (E)-6-((((E)-4-(phenyl)but-3-en-1-yl)oxy)methylene)cyclohexa-2,4-dien-1-one
10.14469/hpc/4103	FAIR data for (E)-6-((((E)-4-(4-cyanophenyl)but-3-en-1-yl)oxy)methylene)cyclohexa-2,4-dien-1-one
10.14469/hpc/4100	FAIR data for (E)-6-((((E)-4-(4-methoxyphenyl)but-3-en-1-yl)oxy)methylene)cyclohexa-2,4-dien-1-one

Associated DOIs

Current dataset ...	DOI	Description
References	10.1039/c8sc04302g	Published article: Reversibility and reactivity in an acid catalyzed cyclocondensation to give furanochromanes – a reaction at the ‘oxonium-Prins’ vs. ‘ortho-quinone methide cycloaddition’ mechanistic nexus
References	10.14469/hpc/4041	Viewing and re-using Computational, Spectroscopic and Crystallographic FAIR Data

Edit