32080-72-1

Upstream product

• 42858-38-8 (E)-cyclododec-2-enone 
• 141-97-9 ethyl acetoacetate 
• 42858-38-8 (E)/(Z)-cyclododec-2-enone 

Downstream Products

• 137567-53-4 (1S,11R,13R)-13-Phenyl-bicyclo[9.3.1]pentadecan-13-ol 
• 137495-34-2 (1R,11S,13S)-13-Phenyl-bicyclo[9.3.1]pentadecan-13-ol 

Relevant academic research and scientific papers

A CONVENIENT ROUTE TO 1,3-CYCLOOCTATETRAENOPHANES

Three cyclooctatetraenes, bridged with methylene groups in a previously unknown 1,3-manner, have been prepared in racemic form by a route involving ultimate disrotatory opening of a suitable constructed bicyclooctatriene precursor.

Is pseudorotation the operational pathway for bond shifting within [8]annulenes? Probe of planarization requirements by 1,3-annulation of the cyclooctatetraene ring. Kinetic analysis of racemization and 2-D NMR quantitation of π-Bond alternation and ring inversion as a function of polymethylene chain length

The chiral 1,3-bridged cyclooctatetraenes 9a-c have been prepared in nine steps from the appropriate 2-cycloalkenone precursors. Following annulation with ethyl acetoacetate to give 15, trans-1,2-dichloroethylene was cycloadded photochemically in a [2 + 2] reaction and a cyclobutene ring was ultimately formed. Once reduction to alcohol 19 was accomplished, dehydration was effected and the bicyclo[4.2.0]octatrienes so generated underwent disrotatory ring opening to deliver the [8]annulenes. The rates of this electrocyclic ring opening were determined in two examples. Polarimetric studies provided quantitative measure of the readiness with which planar dianion formation occurs as a function of loop size. Unexpectedly, attempts to resolve these molecules failed to deliver them in optically active condition because of too rapid enantiomerization via ring inversion and/or bond shifting. The rates of these processes were determined by 2-D dynamic NMR methods, the data revealing that both processes are accelerated relative to nonbridged models. These and related findings are interpreted in terms of a pseudorotation scheme leading to flattened saddle and not planar-alternate transition states. The unique features associated with this mechanistic phenomenon are discussed.