The thermolysis of trans-1 -trimethylsiloxy- 1-vinylcyclotridec-
3-ene (VI-OTMS) led to the formation of two major products: 4-vinylcyclotridecanone
(VII) and cyclopentadec-5-en-l-one (VIII) after
hydrolysis. Ketone VII is produced by a concerted [3, 3] sigmatropic
shift, while ketone VIII is formed by a [1, 3] sigmatropic shift with
a concerted or diradical...
The potassium salts of certain 1-vinylcycloalk-3-en-l-ols have
been found to undergo sigmatropic ring expansion rearrangements in
HMPA. Preliminary investigations of several benzo-substituted medium
ring systems were undertaken in order to determine which of these
was best suited for further study. A synthetic sequence leading to
the formation of 5-methy1-6-viny1-7,8,9,10-tetrahydro-6-benzocyclo-octenol,
which...
Both oxy-Cope and siloxy-Cope rearrangements involve
(1, 3) and (3, 3) sigrnatropic shifts. Both the concerted mechanism,
and the stepwise mechanism via a diradical intermediate are possible.
In a cyclic system such as cis-l-vinylcyclooct-3-en-l-ol, the thermal
rearrangement takes place preferably through a diradical intermediate.
At high temperature, the reaction also...
Part I
The pyrolysis of cis- and trans- 1, 2-divinyl-1- trimethylsiloxy -
cyclohexane, II- and III-TMS, under the same conditions as the
pyrolysis of cis-l-vinyl -1-trimethylsiloxycyclooct-3-ene, I-TMS,
confirms that a sequence of concerted reactions for the rearrangement
of II- and III-TMS to trans-l-trimethylsiloxycyclodec-3-ene,
IV-TMS, is a viable pathway in the...
The (±) 8,9:13,14-diseco-norestradiol, a large ring hormone
analog, and its related derivatives, were prepared by a ring expansion
approach. The key step of this approach is the establishment of the
benzocyclododecenone system via the Caubere reaction. This step
not only provides a favorable ring size, it also sets the necessary...