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...
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...
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...
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...
Part 1
The pyrolysis of cis-1-trimethylsiloxy-1-cyclopr opyl-3-cyclononene in the temperature range 285-350° is described. Instead
of siloxy-Cope rearrangement, undesired desiloxylation took place.
Part 2
Gas-phase pyrolytic rearrangement of 2-phenyl-1-trimethylsiloxy-1-vinylcyclononane was investigated in a static system
in the temperature range 213-330°. It was discovered that
three major products resulted: cis- and...
The potassium salts of a series of 1-vinylcycloalk-3-en-l-ols were found to undergo ring expanding [1, 3]-sigmatropic shifts at 25° when dissolved in hexamethylphosphoramide (HMPA) or 1, 2-dimethoxyethane (DME) with 18-crown-6. The yields and reaction rates were compared with those of the corresponding Siloxy-Cope ring expansions. These anionic cases showed about...
The reactions of cyclodeca-1, 2, 5, 8-tetraene with mercuric salts
in solvents of varying nucleophilicity are described. Instead of forming
the usual oxymercuration products reported for reactions of olefins
and allenes with mercuric salts, the major products obtained in the
present cases result from the initial electrophilic addition of the...