- Radical cyclizations leading to the bicyclo[2.2.1]heptane framework: A new radical approach to (±)-(Z)-β-santalol
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Tandem radical cyclizations of acyclic iodides, including [3-(2-iodoethyl)-6,10-dimethyl-undeca-5,9-dien-1-ynyl]-dimethylphenylsilane lead in good yields to bicyclo[2.2.1]heptane derivatives. The cascade relies on two sequential radical-mediated 5-exo-cyclizations. The radical approach is illustrated with the total synthesis of racemic-(Z)-β-santalol. The results are remarkable, two fused rings and one stereogenic center are formed in a single operation. A new 'coordinated' hydride appeared to be useful in the cascade.
- Pianowski, Zbigniew,Rupnicki, Leszek,Cmoch, Piotr,Staliński, Krzysztof
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p. 900 - 904
(2007/10/03)
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- Stereoselective Syntheses of (+/-)-epi-β-Santalene and (+/-)-epi-β-Santalol
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Stereoselective syntheses of (+/-)-epi-β-santalene (1) and (+/-)-epi-β-santalol (2), minor constituents of East Indian sandalwood oil, are described.The starting material for both syntheses is the tricyclic hemiacetal 4, readily accessible in two steps from norbornene.
- Snowden, Roger L.,Sonnay, Philippe,Ohloff, Guenther
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- East Indian Sandalwood Oil. 2. Stereoselective Synthesis of (+/-)-Epi-β-santalene and (+/-)-Epi-β-santalol
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Acid-catalyzed rearrangement of γ-lactone 6 in the presence of acetonitrile provides a mixture of amide acids, which are readily separated as their ethyl esters 18-20.The major product 18, when subjected to fragmentation, provides esters 21 and 22 (92percent and 8percent, respectively).The structure of 21 has been confirmed by its conversion, via aldehyde 23, to (+/-)-epi-β-santalene (8).Similarly, the structure of 22 has been confirmed by its conversion to (+/-)-α-santalene (3). (+/-)-Epi-cis-β-santalol (9), (+/-)-epi-trans-β-santalol (10), and (+/-)-dihydroepi-β-santalol (11) have also been prepared via aldehyd 23.
- Christenson, Philip A.,Willis, Brian J.
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p. 3068 - 3072
(2007/10/02)
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