Synthetic Application of Hetero-substituted 1,3-Dienes Generated in Situ from Enone Cyclic Acetals and Dithioacetals
Project/Area Number |
05640585
|
Research Category |
Grant-in-Aid for General Scientific Research (C)
|
Allocation Type | Single-year Grants |
Research Field |
Organic chemistry
|
Research Institution | Hokkaido University |
Principal Investigator |
OHKITA Masakazu Hokkaido Univ.Dep.of Science, Instructor, 理学部, 助手 (60211786)
|
Project Period (FY) |
1993 – 1994
|
Project Status |
Completed (Fiscal Year 1994)
|
Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1994: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1993: ¥1,000,000 (Direct Cost: ¥1,000,000)
|
Keywords | Acetals / Enol Ethers / Diels-Alder Reaction / Dithioacetals / ディールス アルダー反応 / 分子内環化付加 / ディールス・アルダー反応 |
Research Abstract |
Recently, we have demonstrated that 2-cyclopent-1-ene ethylene acetal 1 is capable of undergoing the ring-cleavage to afford cyclopenta-1,3-dienol ether 2, which in turn is trapped by dienophiles to give 2-norbornanone ethylene acetals 4. In contrast to the corresponding keto-enol tautomerism, the thermal equilibration between cyclic acetal and its ring-opened enol ether form has been little exploited synthetically. In this study, we examined generality, selectivity, scope, and limitation of this Diels-Alder strategy. The intermediate 2 was detected by UV spectroscopy, and its content relative to 1 at a stationary state at 70゚C in acetonitrile was estimated to be about 0.2%. Of the several solvents examined, acetonitrile was most satisfactory. The addition reactions were highly regioselective and the 1,3-cyclopentadien-2-yl intermediates selectively derived from the corresponding acetal precursors via 1,2-elimination. Dithioacetals of 2-cyclopentenones, which are readily available from the corresponding enones, also react with dienophiles in a similar manner. The reation of dithioacetals were catalyzed with Zn (OTf) _2. The addition of ketene equivalent to (dithio) acetals allowed the convinient preparation of singly acetalized 2,5-norbornadienes.
|
Report
(3 results)
Research Products
(3 results)