Recent Advances in the Synthesis of Indan Systems. A Review

Methodology for the Construction of the Bicyclo[4.3.0]nonane Core

“…Under the same sequence of reduction and protection as prior, the authors were able to generate 24. Further elaboration through their conditions for Still's [2,3]-Wittig rearrangement and hydroboration/oxidation sequence found better regioselectivity for the resulting ketone. Photolysis was attempted, and found to give the improper stereochemistry, thus prompting epimerization with NaOCH 3 .…”

“…This prompted the development of the Hajos-Parrish dione (1) and its 6,6-fused analog, the Wieland-Miescher diketone (2), shown in Figure 2. The present section will detail the development, use, and elaboration of scaffolds stemming from 1 for natural product synthesis.…”

“…Treatment with LiAlH 4 , followed by protection of the resulting alcohol with SEM-Cl led to the distannyl 19. Lithiation at −78 • C with warming allowed for Still's [2,3]-Wittig rearrangement, which was protected as the methoxyethoxymethyl (MEM) ether (20). Hydroboration followed by oxidative cleavage leading to 21 found issues with regioselectivity from 1, typically giving a mix with 22.…”

“…Notably, the hydrindane moiety often contains a significant portion of the stereochemistry contained in the natural product; thus presenting a wealth of opportunity for method development and posing a synthetic challenge [2]. Over the past forty years, different strategies have been employed to showcase the utility of reaction sequences leading to the hydrindane nucleus, with most targeting the thermodynamically unfavorable trans isomer.…”

The reaction of 1-tetralones with thallium trinitrate supported on clay: ring contraction vs alpha-oxidation

“…The most common approaches for synthesizing such molecules are either the direct modification of substrates that already bear the indan skeleton or the cycloaddition reactions 1 .…”