Addition of benzyl ethers to alkynes: a metal-free synthesis of 1-isochromenes

Bromotrimethylsilane (TMSBr)-promoted intramolecular cyclization of ( o -arylethynyl)benzyl ethers to form 1 H -isochromenes at room temperature is reported. Further studies indicated that vinyl carbocations are the reaction intermediates which are stabilized by the conjugated aryl groups. Thus, O -...

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Published inOrganic & biomolecular chemistry Vol. 19; no. 47; pp. 139 - 142
Main Authors Kuan, Tzu-Hsuan, Kotipalli, Trimurtulu, Chen, Cheng-Chun, Hou, Duen-Ren
Format Journal Article
Published 08.12.2021
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Summary:Bromotrimethylsilane (TMSBr)-promoted intramolecular cyclization of ( o -arylethynyl)benzyl ethers to form 1 H -isochromenes at room temperature is reported. Further studies indicated that vinyl carbocations are the reaction intermediates which are stabilized by the conjugated aryl groups. Thus, O -addition of benzyl ethers/tetrahydropyrans to alkynes was achieved under metal-free, acidic conditions. These reaction conditions were compatible with an alkynyl Prins reaction; therefore, 1 H -isochromenes were produced directly from alkynyl benzaldehydes and alkynyl alcohols using a one-pot procedure. The synthesis of 1 H -isochromenes was achieved by addition of benzyl ethers to alkynes, activated with bromotrimethylsilane (TMSBr).
Bibliography:10.1039/d1ob01941d
1
For ESI and crystallographic data in CIF or other electronic format see DOI
13
C
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2068139
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Electronic supplementary information (ESI) available: Experimental procedures, X-ray crystallography of
ISSN:1477-0520
1477-0539
DOI:10.1039/d1ob01941d