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3‐Alkyl‐1‐benzoxepin‐5‐on‐Derivate und 2‐Alkyl‐1, 4‐naphthochinone aus 2‐Acylaryl‐propargyläthern
Author(s) -
JacksonMülly Martha,
Zsindely Janos,
Schmid Hans
Publication year - 1976
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19760590233
Subject(s) - chemistry , propargyl , alkyl , medicinal chemistry , yield (engineering) , alkylation , stereochemistry , base (topology) , organic chemistry , catalysis , mathematical analysis , materials science , mathematics , metallurgy
3‐Alkyl‐1‐benzoxepin‐5‐one derivatives and 2‐alkyl‐1,4‐naphtoquinones from 2‐acylaryl propargyl ethers. It was found that 3‐alkyl‐1‐benzoxepin‐5(2 H )‐ones of type B can be synthesized by treating 2‐acylaryl propargyl ethers of type A with sodium methylsulfinyl methide (NaMSM, dimesyl sodium) ( Scheme 13 ). Oxepinone derivatives of type B undergo ring contraction with base (also NaMSM) to yield the quinol derivatives C which, oxidize (during work‐up), if R 2 = H, to the 1,4‐naphthoquinones D ( Scheme 13 ). The propargyl ethers used are listed in Scheme 1 . The naphthalene derivatives 1 and 3 give oxepinones ( E ‐ 9 and a mixture of 14/15 respectively), whereas the expected oxepinone from 2 is transformed directly into the quinone 11 ( Scheme 2, 3 and 5 ). Isomerizations of 2‐acetylphenyl propargyl ethers ( 4, 5 and 6 ) ( Schemes 6, 7 and 8) are less successful because of side reactions. If however the acetyl group is replaced by a propionyl or substituted propionyl group (as in ethers 7 and 8 ) oxepinones are obtained again in good yield ( Scheme 9 ). The mechanistic pathway for the transformation of naphthyl propargyl ethers (and phenyl derivatives) under influence of NaMSM is shown in Scheme 10. The base‐catalysed conversion of 4‐phenyl‐l‐benzoxepin‐5( 2H )‐one,benzo[ f ]furo[2,3‐ c ](10 H )‐oxepin‐4‐oncsand 3‐methoxy‐G,11‐ dihydro‐dibenzo[ b, e ]loxepin‐11‐oneinto thc corresponding quinones has been reported [13] [20] [21]. The conversion of 2‐acylaryl propargyl others via the isolable benzoxepin‐5‐one derivativcs or directly into the specifically substituted 1,4‐naphthoquinone derivatives is of synthetic interest.