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1,3‐Dipolar Cycloaddition of Benzonitrile Oxide to Substituted 4,5‐Dihydro‐3‐methylene‐2(3 H )‐furanones
Author(s) -
Štverková Slávka,
Žák Zdirad,
Jonas Jaroslav
Publication year - 1993
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.1993199301189
Subject(s) - benzonitrile , chemistry , cycloaddition , methylene , medicinal chemistry , diastereomer , oxide , 1,3 dipolar cycloaddition , stereochemistry , homo/lumo , organic chemistry , molecule , catalysis
Benzonitrile oxide cycloadds to the CC bond of substituted 4,5‐dihydro‐3‐methylene‐2(3 H )‐furanones 1a–1g . Thus, ( E )‐ 1a and ( E )‐ 1b are converted into the corresponding isoxazolinespirodihydrofuranones (4 RS ,5 RS )‐ 2a and (4 RS ,5 RS )‐ 2b , and ( E )‐ 1c is converted into a mixture of isomers (4 RS ,5 RS )‐ 2c and (4 RS ,5 RS )‐ 3c . The reactions of ( E )‐ 1d–1g yield mixtures of the corresponding diastereomeric isoxazolinespirodihydrofuranones (4 RS ,5 RS ,8 RS )‐ 2d and (4 RS ,5 RS ,8 SR )‐ 2d , (4 RS ,5 RS )‐ 3e and (4 RS ,5 SR )‐ 3e , (4 RS ,5 RS )‐ 3f and (4 RS ,5 SR )‐ 3f , (4 RS ,5 RS )‐ 3g and (4 RS ,5 SR )‐ 3g . The addition of benzonitrile oxide to ( Z )‐ 1a gives (4 RS ,5 SR )‐ 2a and 4a . In the cycloaddition with ( E )‐ 1a the p ‐tolylsulfonyloxy group in the intermediate (4 RS ,5 RS )‐ 2a is partially replaced by chlorine to give (4 RS ,5 RS )‐ 2h . – The structures of (4 RS ,5 RS )‐ 2h , (4 RS ,5 RS )‐ 3e , (4 RS ,5 SR )‐ 3e , and 4a are determined by X‐ray analysis. The 1 H‐ and 13 C‐NMR spectra of the products are discussed and the reaction course is rationalized on the basis of HOMO‐LUMO energy gaps.