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Volumn 68, Issue 5, 2003, Pages 1938-1946

Cyclic allene intermediates in intramolecular dehydro Diels-Alder reactions: Labeling and theoretical cycloaromatization studies

Author keywords

[No Author keywords available]

Indexed keywords

AROMATIZATION; CARBON TETRACHLORIDE; SOLVENTS; SYNTHESIS (CHEMICAL);

EID: 84962439644     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo0265380     Document Type: Article
Times cited : (60)

References (68)
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    • note
    • Keto-enol isomerization of 3-hydroxy-1,2,4-cyclohexatriene to cyclohexa-2,5-dien-1-one through intramotecular proton transfer has recently been studied at the MP2(fc)/6-31G** level. The computed barrier to this process was only 6.7 kcal/mol, which suggests that the trapping of hydrogens in cyclic allenes made available by protic solvents may be a fast reaction. See ref 9c.
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    • See ref 9d, see also comments in ref 56 of this work
    • (a) See ref 9d, see also comments in ref 56 of this work.
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    • For CC calculations orbitals were expressed as spherical harmonics whereas a Cartesian expression was used in MCQDTP2 calculations
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    • note
    • 32 (2.0 kcal/mol) and also quite close to the BLYP value obtained by Schreiner (5.9 kcal/mol). All these values suggest that racemization of 4 is a very fast process (Scheme 3). However, post-HF methods such as BCCD (ref 9d) and CASPT2 and MRCI (ref 34) indicate a higher value of about 10 kcal/mol.
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    • note
    • The apparent discrepancy between experimental and theoretical reaction enthalpies has recently been resolved; see ref 34.
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    • note
    • The QCISD/6-311G** barriers to [1,5] H shifts in 1,3-cyclopentadiene and 1,3-pentadiene at 0 K are 29.7 and 40.0 kcal/mol, respectively. See ref 12.
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    • note
    • The transition structures 6 and 8 were also computed in ref 19, with geometric results very close to ours.
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    • note
    • Hopf/Schreiner found that benzo[c]annulation of cyclohexatriene increased the barrier to aromatization via path b; see ref 9d.
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    • note
    • Calculations for this set of points minimizes the effects of σ bonds on NICS.
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    • note
    • 1H NMR of the purified product.
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    • note
    • 5 in benzene, followed by treatment with TBAF).


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.