The polar reaction, N-cyclo " pen " tenyl pyrrolidine nucleophilic addition to the diazo compound, proceeds 1, 500 times faster in polar DMSO than in non-polar decalin.
12.
An approach to the " trans "-decalin ring system of salvinorin A has been described by Forsyth ( " et al " . ) utilizing an intramolecular Diels-Alder reaction / Tsuji allylation strategy.
13.
On the other hand, a close analog of this reaction, N-cyclo " hex " enyl pyrrolidine 1, 3-dipolar cycloaddition to dimethyl diazomalonate, is sped up only 41-fold in DMSO relative to decalin.
14.
The described synthesis was a relay approach, with the required, heavily functionalized decalin intermediate being made by total synthesis on a small scale, but being derived from the natural product itself for the gram-scale operations required to complete the synthesis.
15.
The one common atom connecting the participating rings distinguishes spiro compounds from other bicyclics : from " isolated ring compounds " like biphenyl that have no connecting atoms, from " fused ring compounds " like decalin having two rings linked by two adjacent atoms, and from " bridged ring compounds " like norbornane with two rings linked by two non-adjacent atoms.
