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Synthesis of 1,2,3,4‐Tetrahydro‐1,2‐dimethylidenenaphthalene: A Reactive s‐ cis ‐Butadiene Undergoing Highly Chemo‐ and Regioselective Cyclodimerization
Author(s) -
Roversi Elena,
Vogel Pierre,
Schenk Kurt
Publication year - 2002
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 - 10.1002/1522-2675(200205)85:5<1390::aid-hlca1390>3.0.co;2-7
Subject(s) - regioselectivity , chemistry , diene , diradical , dimer , reactivity (psychology) , medicinal chemistry , dehydrohalogenation , phenanthrene , 1,3 butadiene , photochemistry , organic chemistry , catalysis , medicine , natural rubber , physics , alternative medicine , pathology , nuclear physics , singlet state , excited state
1,2,3,4‐Tetrahydro‐1,2‐dimethylidenenaphthalene 11 has been derived in three steps from tetralone. In the condensed state and at −80°, it undergoes a highly chemo‐ and regioselective cyclodimerization to give 3,3′,4,4′‐tetrahydro‐2‐methylidenespiro[naphthalene‐1(2 H ),2′(1′ H )‐phenanthrene] ( 14 ), the structure of which has been established by single‐crystal X‐ray‐diffraction analysis. Dimer 14 undergoes cycloreversion to diene 11 under flash‐pyrolysis conditions. The reaction of diene 11 with SO 2 occurs without acid promoter at −80° and gives a mixture of (±)‐1,4,5,6‐tetrahydronaphth[1,2‐ d ][1,2]oxathiin 2‐oxide ( 23 ; a single sultine), 1,3,4,5‐tetrahydronaphtho[1,2‐ c ]thiophene 2,2‐dioxide ( 25 ), and dimer 14 . The high reactivity of diene 1 in its Diels‐Alder cyclodimerization and its highly regioselective hetero‐ Diels‐Alder addition with SO 2 can be interpreted in terms of the formation of relatively stable diradical intermediates or by concerted processes with transition states that can be represented as diradicaloids.