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Abstract
Oxetanes are important motifs for drug discovery and are valuable templates in organic synthesis. Much of their use as synthetic intermediates exploits their inherent strain, often resulting in chain extensions at the expense of the heterocycle. Modifications on the carbon alpha to the oxygen of oxetanes, such as the C═O of β-lactones, extend the modes of reactivity. Nevertheless, the outcomes are still largely predictable. On the other hand, other alpha modifications, such as a ═CH2, a spiro-oxiranyl moiety, or a spiro-cyclopropyl group, increase strain and open pathways not available to simple oxetanes or β-lactones. Methods in generating 2-methyleneoxetanes, 1,5-dioxaspiro[3.2]hexanes, and 4-oxaspiro[2.3]hexanes have been developed by us and others. To date, reactions of these systems have sometimes been predictable, but often the outcomes have been unexpected. This has provided fertile ground for thinking about what controls reactivity and what other reaction pathways might be accessible to these strain-heightened oxetanes.This Account summarizes the published literature on the most straightforward approaches to 2-methyleneoxetanes, dioxaspirohexanes, and oxaspirohexanes and on their reactivity. In contrast to simple oxetanes, reactions of 2-methyleneoxetanes with nucleophiles at C4 release an enolate rather than an alkoxide. Also, 2-methyleneoxetanes can be converted to homopropargyl alcohols or undergo a silicon accelerated isomerization/electrocyclic ring opening, processes accessible only because of the exocyclic double bond. In addition, oxetane oxocarbenium ions, derived from protonation of the enol ether, can react with nucleophiles to provide 2,2-disubstituted oxetanes. Oxaspirohexanes are readily prepared by Simmons-Smith cyclopropanation of 2-methyleneoxetanes. These unusual systems undergo a variety of substituent dependent rearrangements in the presence of the Lewis acid BF3·Et2O. In addition, upon treatment with Zeise's dimer, oxaspirohexanes are transformed to synthetically useful 3-methylenetetrahydrofurans. Dioxaspirohexanes are easily accessed by dimethyldioxirane oxidation of 2-methyleneoxetanes. Predictably, dioxaspirohexanes react with many nucleophiles to give α-functionalized-β'-hydroxy ketones. Unexpectedly, 2,2-disubstituted oxetanes can also be selectively produced. This latter pathway has led to further unusual transformations, illuminating computational studies, and novel routes to biologically relevant molecules.
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Affiliation(s)
- Jason An
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, United States
| | - Louis P. Riel
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, United States
| | - Amy R. Howell
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, United States
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Çetinkaya Y, Maraş A, Göksu S. Insight into the intramolecular interactions of trans-2-azidocycloalk-3-en-1-ols and trans-2-azidocycloalk-3-en-1-yl acetates: A theoretical study. Tetrahedron 2021. [DOI: 10.1016/j.tet.2021.132272] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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3
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Liu R, Wei Z, Wang J, Liu Y, Xue H. Highly selective hydrosilylation of equilibrating allylic azides. Chem Commun (Camb) 2020; 56:5038-5041. [PMID: 32242569 DOI: 10.1039/d0cc01316a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The Pt-catalyzed hydrosilylation of equilibrating allylic azides is reported. The reaction provides only one out of four possible hydrosilylation products in good yields and with very high chemoselectivity (alk-1-ene vs. alk-2-ene), regioselectivity (linear vs. branched), and excellent functional group tolerance.
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Affiliation(s)
- Ruzhang Liu
- College of Chemistry & Chemical Engineering, Yangzhou University, 180 Siwangting Rd., Yangzhou 225002, China.
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Tjeng AA, Handore KL, Batey RA. Stereocontrolled Microwave-Assisted Domino [3,3]-Sigmatropic Reactions: A Winstein-Overman Rearrangement for the Formation of Differentiated Contiguous C-N Bonds. Org Lett 2020; 22:3050-3055. [PMID: 32223252 DOI: 10.1021/acs.orglett.0c00801] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A domino [3,3]-sigmatropic rearrangement sequence employing a sequential reversible allylic azide rearrangement followed by an irreversible Overman reaction provides a new route to the formation of two contiguous C-N bonds. The reaction occurs in a stereocontrolled fashion in two steps from readily available alkenyl epoxides via initial azide anion ring opening of the epoxides.
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Affiliation(s)
- Andy A Tjeng
- Davenport Research Laboratories, Dept. of Chemistry, University of Toronto, 80 St. George St., Toronto, ON, M5S 3H6, Canada
| | - Kishor L Handore
- Davenport Research Laboratories, Dept. of Chemistry, University of Toronto, 80 St. George St., Toronto, ON, M5S 3H6, Canada
| | - Robert A Batey
- Davenport Research Laboratories, Dept. of Chemistry, University of Toronto, 80 St. George St., Toronto, ON, M5S 3H6, Canada
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5
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Carlson AS, Topczewski JJ. Allylic azides: synthesis, reactivity, and the Winstein rearrangement. Org Biomol Chem 2019; 17:4406-4429. [PMID: 30969292 PMCID: PMC6530792 DOI: 10.1039/c8ob03178a] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Organic azides are useful synthetic intermediates, which demonstrate broad reactivity. Unlike most organic azides, allylic azides can spontaneously rearrange to form a mixture of isomers. This rearrangement has been named the Winstein rearrangement. Using allylic azides can result in low yields and azide racemization in some synthetic contexts due to the Winstein rearrangement. Effort has been made to understand the mechanism of the Winstein rearrangement and to take advantage of this process. Several guiding principles can be used to identify which azides will produce a mixture of isomers and which will resist rearrangement. Selective reaction conditions can be used to differentiate the azide isomers in a dynamic manner. This review covers all aspects of allylic azides including their synthesis, their reactivity, the mechanism of the Winstein rearrangement, and reactions that can selectively elaborate an azide isomer. This review covers the literature from Winstein's initial report to early 2019.
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Affiliation(s)
- Angela S Carlson
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA.
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Porter MR, Shaker RM, Calcanas C, Topczewski JJ. Stereoselective Dynamic Cyclization of Allylic Azides: Synthesis of Tetralins, Chromanes, and Tetrahydroquinolines. J Am Chem Soc 2018; 140:1211-1214. [PMID: 29303567 PMCID: PMC5989720 DOI: 10.1021/jacs.7b11299] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
This report describes the stereoselective synthesis of 3-azido-tetralins, -chromanes, and -tetrahydroquinolines via a tandem allylic azide rearrangement/Friedel-Crafts alkylation. Exposure of allylic azides with a pendant trichloroacetimidate to catalytic quantities of AgSbF6 proved optimal for this transformation. This cascade successfully differentiates the equilibrating azide isomers, providing products in excellent yield and selectivity (>25 examples, up to 94% yield and >25:1 dr). In many cases, the reactive isomer is only a trace fraction of the equilibrium mixture, keenly illustrating the dynamic nature of these systems. We demonstrate the utility of this process via a synthesis of hasubanan.
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Affiliation(s)
- Matthew R. Porter
- Department of Chemistry, University of Minnesota Twin Cities, Minneapolis, Minnesota 55455, United States
| | - Rami M. Shaker
- Department of Chemistry, University of Minnesota Twin Cities, Minneapolis, Minnesota 55455, United States
| | - Cristian Calcanas
- Department of Chemistry, University of Minnesota Twin Cities, Minneapolis, Minnesota 55455, United States
| | - Joseph J. Topczewski
- Department of Chemistry, University of Minnesota Twin Cities, Minneapolis, Minnesota 55455, United States
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Lee SJ, Yang HW, Han TH, Yoon CM. Synthesis of Aryl-( E)-2-(azidomethyl)alkenoate and Aryl-( Z)-2-(azidomethyl)acrylonitrile from Aryl Aldehydes and Activated Alkenes via One-Pot Way. B KOREAN CHEM SOC 2016. [DOI: 10.1002/bkcs.10751] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Sang-Jin Lee
- Department of Advanced Material Chemistry; Korea University; Sejong-si, 339-770 South Korea
| | - Hae-Won Yang
- Department of Advanced Material Chemistry; Korea University; Sejong-si, 339-770 South Korea
| | - Tae-Hwi Han
- Department of Advanced Material Chemistry; Korea University; Sejong-si, 339-770 South Korea
| | - Cheol Min Yoon
- Department of Advanced Material Chemistry; Korea University; Sejong-si, 339-770 South Korea
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Vale JR, Siopa F, Branco PS, Afonso CAM. Ring Opening of 6-Azabicyclo[3.1.0]hex-3-en-2-ols in Water under Mild Conditions. European J Org Chem 2016. [DOI: 10.1002/ejoc.201501468] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Vekariya RH, Liu R, Aubé J. A concomitant allylic azide rearrangement/intramolecular azide-alkyne cycloaddition sequence. Org Lett 2014; 16:1844-7. [PMID: 24635056 PMCID: PMC3993870 DOI: 10.1021/ol500011f] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
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An intramolecular Huisgen cycloaddition
of an interconverting set
of isomeric allylic azides with alkynes affords substituted triazoles
in high yield. The stereoisomeric vinyl-substituted triazoloxazines
formed depend on the rate of cycloaddition of the different allylic
azide precursors when the reaction is carried out under thermal conditions.
In contrast, dimerized macrocyclic products were obtained when the
reaction was done using copper(I)-catalyzed conditions, demonstrating
the ability to control the reaction products through changing conditions.
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Affiliation(s)
- Rakesh H Vekariya
- Department of Medicinal Chemistry, University of Kansas , Lawrence, Kansas 66045, United States
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Farber E, Rudnitskaya A, Keshipeddy S, Lao KS, Gascón JA, Howell AR. Silicon Acceleration of a Tandem Alkene Isomerization/Electrocyclic Ring-opening of 2-Methyleneoxetanes to α,β-Unsaturated Methylketones. J Org Chem 2013; 78:11213-20. [DOI: 10.1021/jo4014645] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Elisa Farber
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, United States
| | - Aleksandra Rudnitskaya
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, United States
| | - Santosh Keshipeddy
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, United States
| | - Kendricks S. Lao
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, United States
| | - José A. Gascón
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, United States
| | - Amy R. Howell
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, United States
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Liu R, Gutierrez O, Tantillo DJ, Aubé J. Stereocontrol in a combined allylic azide rearrangement and intramolecular Schmidt reaction. J Am Chem Soc 2012; 134:6528-31. [PMID: 22490078 DOI: 10.1021/ja300369c] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pre-equilibration of an interconverting set of isomeric allylic azides is coupled with an intramolecular Schmidt reaction to afford substituted lactams stereoselectively. The effect of substitution and a preliminary mechanistic study are reported. The synthetic potential of this method is demonstrated in the context of an enantioselective synthesis of an advanced intermediate leading toward pinnaic acid.
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Affiliation(s)
- Ruzhang Liu
- Department of Medicinal Chemistry, Delbert M. Shankel Structural Biology Center, University of Kansas, 2034 Becker Drive, Lawrence, Kansas 66045, USA
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Gómez AM, Pedregosa A, Uriel C, Valverde S, López JC. 1-exo-Alkylidene-2,3-anhydrofuranoses: Valuable Synthons in the Preparation of Furanose-Based Templates. European J Org Chem 2010. [DOI: 10.1002/ejoc.201000612] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Surendra Reddy P, Ravi V, Sreedhar B. Efficient synthesis of allylic azides and one-pot regioselective synthesis of 1,4-disubstituted 1,2,3-triazoles from homoallyl alcohols. Tetrahedron Lett 2010. [DOI: 10.1016/j.tetlet.2010.05.097] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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14
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Synthesis of diastereoisomeric 6-deoxy-d-allal- and 6-deoxy-d-galactal-derived allyl epoxides and examination of the regio- and stereoselectivity in nucleophilic addition reactions. Comparison with the corresponding 6-O-functionalized allyl epoxides. Tetrahedron 2008. [DOI: 10.1016/j.tet.2008.06.039] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Klepper F, Jahn EM, Hickmann V, Carell T. Synthese des tRNA-Nucleosids Queuosin unter Verwendung eines chiralen Allylazid-Intermediats. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200604579] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Klepper F, Jahn EM, Hickmann V, Carell T. Synthesis of the Transfer-RNA Nucleoside Queuosine by Using a Chiral Allyl Azide Intermediate. Angew Chem Int Ed Engl 2007; 46:2325-7. [PMID: 17310487 DOI: 10.1002/anie.200604579] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Florian Klepper
- Department of Chemistry and Biochemistry, Ludwig-Maximilians-Universität, Butenandtstrasse 5-13, 81377 Münich, Germany
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Fast and efficient preparation of Baylis–Hillman-derived (E)-allylic azides and related compounds in aqueous medium. Tetrahedron 2006. [DOI: 10.1016/j.tet.2006.09.059] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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