Non-bonding 1,5-S•••O interactions govern chemo- and enantioselectivity in isothiourea-catalyzed annulations of benzazoles

Emily R. T. Robinson; Daniel M.  Walden; Charlene Fallan; Mark D. Greenhalgh; Paul Ha-Yeon Cheong; Andrew D. Smith

doi:10.1039/C6SC00940A

Non-bonding 1,5-S•••O interactions govern chemo- and enantioselectivity in isothiourea-catalyzed annulations of benzazoles

Emily R. T. Robinson, Daniel M. Walden, Charlene Fallan, Mark D. Greenhalgh, Paul Ha-Yeon Cheong, Andrew D. Smith

Research output: Contribution to journal › Article › peer-review

Abstract

Isothiourea-catalyzed annulations between 2-acyl benzazoles and α,β-unsaturated acyl ammonium intermediates are selectively tuned to form either lactam or lactone heterocycles in good yields (up to 95%) and high ee (up to 99%) using benzothiazole or benzoxazole derivatives, respectively. Computation gives insight into the significant role of two 1,5-S•••O interactions in controlling the structural preorganization and chemoselectivity observed within the lactam synthesis with benzothiazoles as nucleophiles. When using benzazoles the absence of a second stabilizing non-bonding 1,5-S•••O interaction leads to a dominant CH•••O interaction in determining structural preorganization and lactone formation.

Original language	English
Pages (from-to)	6919-6927
Number of pages	9
Journal	Chemical Science
Volume	7
Issue number	12
Early online date	4 Jul 2016
DOIs	https://doi.org/10.1039/C6SC00940A
Publication status	Published - 1 Dec 2016

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10.1039/C6SC00940ALicence: CC BY

Smith_2016_CS_Benzazoles_CC
This is an Open Access article, which is licensed under a Creative Commons Attribution 3.0 Unported Licence.
Final published version, 1.5 MBLicence: CC BY

ERC Starting Grant EnolCat: Emulating nature: Reaction diversity and understanding through asymmetric catalysis
Smith, A. D. (PI)
European Commission
1/10/11 → 30/06/17
Project: Standard
RS Uni Research Fellowship Renewal 2010: University Research Fellowship - Cabranes ans Lewis Bases as Organocatalysts Synthetic Applications
Smith, A. D. (PI)
The Royal Society
1/10/10 → 30/09/13
Project: Fellowship

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@article{9dffa39d0ff34a5a92276987ea806800,

title = "Non-bonding 1,5-S•••O interactions govern chemo- and enantioselectivity in isothiourea-catalyzed annulations of benzazoles",

abstract = "Isothiourea-catalyzed annulations between 2-acyl benzazoles and α,β-unsaturated acyl ammonium intermediates are selectively tuned to form either lactam or lactone heterocycles in good yields (up to 95%) and high ee (up to 99%) using benzothiazole or benzoxazole derivatives, respectively. Computation gives insight into the significant role of two 1,5-S•••O interactions in controlling the structural preorganization and chemoselectivity observed within the lactam synthesis with benzothiazoles as nucleophiles. When using benzazoles the absence of a second stabilizing non-bonding 1,5-S•••O interaction leads to a dominant CH•••O interaction in determining structural preorganization and lactone formation.",

author = "Robinson, {Emily R. T.} and Walden, {Daniel M.} and Charlene Fallan and Greenhalgh, {Mark D.} and Cheong, {Paul Ha-Yeon} and Smith, {Andrew D.}",

note = "We thank the Royal Society (URF to ADS), the EPSRC (ERTR – grant code EP/J500549/1) and the European Research Council under the European Union{\textquoteright}s Seventh Framework Programme (FP7/2007-2013) ERC grant agreement n° 279850 (CF). We also thank the EPSRC UK National Mass Spectrometry Facility at Swansea University. PHYC is the Vicki & Patrick F. Stone Scholar of Oregon State University and gratefully acknowledges financial support from the Stone Family & the National Science Foundation (NSF, CHE-1352663), and the computing infrastructure in part provided by the NSF Phase-2 CCI, Center for Sustainable Materials Chemistry (NSF CHE-1102637). DMW also acknowledges financial support from the Johnson Research Fellowship.",

year = "2016",

month = dec,

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doi = "10.1039/C6SC00940A",

language = "English",

volume = "7",

pages = "6919--6927",

journal = "Chemical Science",

issn = "2041-6520",

publisher = "Royal Society of Chemistry",

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T1 - Non-bonding 1,5-S•••O interactions govern chemo- and enantioselectivity in isothiourea-catalyzed annulations of benzazoles

AU - Robinson, Emily R. T.

AU - Walden, Daniel M.

AU - Fallan, Charlene

AU - Greenhalgh, Mark D.

AU - Cheong, Paul Ha-Yeon

AU - Smith, Andrew D.

N1 - We thank the Royal Society (URF to ADS), the EPSRC (ERTR – grant code EP/J500549/1) and the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013) ERC grant agreement n° 279850 (CF). We also thank the EPSRC UK National Mass Spectrometry Facility at Swansea University. PHYC is the Vicki & Patrick F. Stone Scholar of Oregon State University and gratefully acknowledges financial support from the Stone Family & the National Science Foundation (NSF, CHE-1352663), and the computing infrastructure in part provided by the NSF Phase-2 CCI, Center for Sustainable Materials Chemistry (NSF CHE-1102637). DMW also acknowledges financial support from the Johnson Research Fellowship.

PY - 2016/12/1

Y1 - 2016/12/1

N2 - Isothiourea-catalyzed annulations between 2-acyl benzazoles and α,β-unsaturated acyl ammonium intermediates are selectively tuned to form either lactam or lactone heterocycles in good yields (up to 95%) and high ee (up to 99%) using benzothiazole or benzoxazole derivatives, respectively. Computation gives insight into the significant role of two 1,5-S•••O interactions in controlling the structural preorganization and chemoselectivity observed within the lactam synthesis with benzothiazoles as nucleophiles. When using benzazoles the absence of a second stabilizing non-bonding 1,5-S•••O interaction leads to a dominant CH•••O interaction in determining structural preorganization and lactone formation.

AB - Isothiourea-catalyzed annulations between 2-acyl benzazoles and α,β-unsaturated acyl ammonium intermediates are selectively tuned to form either lactam or lactone heterocycles in good yields (up to 95%) and high ee (up to 99%) using benzothiazole or benzoxazole derivatives, respectively. Computation gives insight into the significant role of two 1,5-S•••O interactions in controlling the structural preorganization and chemoselectivity observed within the lactam synthesis with benzothiazoles as nucleophiles. When using benzazoles the absence of a second stabilizing non-bonding 1,5-S•••O interaction leads to a dominant CH•••O interaction in determining structural preorganization and lactone formation.

U2 - 10.1039/C6SC00940A

DO - 10.1039/C6SC00940A

M3 - Article

SN - 2041-6520

VL - 7

SP - 6919

EP - 6927

JO - Chemical Science

JF - Chemical Science

IS - 12

ER -

Non-bonding 1,5-S•••O interactions govern chemo- and enantioselectivity in isothiourea-catalyzed annulations of benzazoles

Abstract

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Projects

ERC Starting Grant EnolCat: Emulating nature: Reaction diversity and understanding through asymmetric catalysis

RS Uni Research Fellowship Renewal 2010: University Research Fellowship - Cabranes ans Lewis Bases as Organocatalysts Synthetic Applications

Cite this