3400-78-0Relevant articles and documents
Preparation of Optically Active (4aα,8aβ)-Octahydro-4a-methyl-8-methylene-2(1H)-naphthalenone, a Key Intermediate for the Enantioselective Synthesis of Eudesmane Sesquiterpenes
Utaka, Masanori,Fujii, Yasuyuki,Takeda, Akira
, p. 1103 - 1104 (1986)
The titled optically active methylene ketone was prepared in 45percent ee from 3-methyl-1,2-cyclohexanedione by use of a novel asymmetric Michael addition with (R,R)-(-)-2,3-butanediol as chiral auxiliary.
Samarium diiodide-promoted intramolecular ketone-ester coupling reaction: Novel cyclization and ring expansion pathway
Iwaya, Kazuki,Nakamura, Momoe,Hasegawa, Eietsu
, p. 5067 - 5070 (2007/10/03)
When ethyl 2-substituted-1-indanone-2-carboxylates were treated with samarium diiodide (SmI2), ring expansion products such as 3-substituted-1,2-naphthoquinones were isolated. Alcohols were also obtained as the mixture of cis- and trans-isomers of hydroxy and ester substituents. A reaction mechanism involving intramolecular addition of samarium ketyl radicals to ester substituents followed by ring expansion was proposed for the formation of the one-carbon homologated products. Similarly, reaction of ethyl 1-substituted-2-oxo-1-cyclopentanecarboxylates with SmI2 produced 3-substituted-2-hydroxy-2-cyclohexenones along with the corresponding alcohols.
A tandem Horner-Emmons olefination-gonjugate addition approach to the synthesis of 1,5-Disubstituted-6-azabicyclo[3.2.1]octanes based on the AE ring structure of the norditerpenoid alkaloid methyllycaconitine
Callis, David J.,Thomas, Noel F.,Pearson, David P. J.,Potter, Barry V. L.
, p. 4634 - 4640 (2007/10/03)
A novel Horner-Emmons olefination conjugate addition reaction of N-acetylamides to form 1,5-disubstituted-6-azabicyclo[3.2.1]octanes with two bridgehead quarternary carbon centers is reported. This reaction is a key step in an approach to the synthesis of small ring analogues based on the AE ring structure of the Delphinium norditerpenoid, methyllycaconitine (MLA) (1). Initially, 3-(hydroxymethyl)cyclohex-2-en-1-one (10) was selected as the starting material to these structures, but its generation proved inefficient. In contrast, the synthesis of 3-[(phenylthio)methyl]cyclohex-2-en-1-one (6) and 3-(1,3-dithian-2-yl)cyclohex-2-en-1-one (11) proceeded in good yield. Subsequent hydrocyanation, ketalization, reduction, acetylation, deprotection of the acetal, and Horner-Emmons olefination-conjugate addition reaction to form 1-[(phenylthio)methyl]-5-[(ethoxycarbonyl)methyl]-6-acetamido-6-azabicyclo[3.2. 1]octane(28), 1-(1,3-dithian-2-yl)-5-[(ethoxycarbonyl)methyl]-6-acetyl-6-azabicyclo[3.2.1] octane (29), respectively, are reported, as well as for readily available 3-methylcyclohex-2-en-1-one (12). Studies on the Pummerer rearrangement of 28 and subsequent desulfurization and reduction to form an hydroxymethyl-substituted azabicyclo[3.2.1.]octane (40) and then selective protection to form a protected hydroxyethyl N-ethyl (hydroxymethyl)azabicyclo-[3.2.1]octane (3) are also described.
