cyclization

This has been found via the cyclization in the figure below.

In general, radical cyclization to produce small rings is difficult.

The synthesis up to here is well known, though process after the first cyclization was unclear.

Whatever the mechanism, the transition state of cyclization is highly polarized.

In the cyclization of 1, for instance, only the cyclopropane product 2 is observed.

Under conditions of kinetic control, 5-exo cyclization takes place preferentially.

Endo cyclization is observed most often when small or large rings are involved.

The final step is based on the intramolecular cyclization of an aminal.

Their approach employed an aryne cyclization to close the final ring of the natural product.

This step is initiated by the elimination of the diphosphate group, a type A cyclization.

This result is attributed to better orbital overlap in the S2 transition state for cyclization.

It has also been found though that the cyclization can proceed in synclinal orientation.

Three conditions must be met for an efficient radical cyclization to take place:

It is a cyclization reaction: it makes new ring of atoms.

In the transition state for cyclization, the small substituent points toward the alkene.

Once the cyclization has occurred, an oxyallyl cation is formed.

Five- and six-membered rings are the most common sizes produced by radical cyclization.

Initial cyclization probably gives biyclogermacrene in an enzyme bound form.

This causes cyclization and gives rise to 2,3-dihydrodipicolinate.

However, cyclization takes place in a stepwise fashion and does not exhibit stereospecificity.

This precursor is treated with base to induce cyclization.

Extensions of the Nazarov cyclization are generally also subsumed under the same name.

Cyclization and tautomerization will produce the desired product (6).

The Nazarov cyclization reaction is named after him.

The compound can be synthesized in a Bergman cyclization.