221149-05-9

Upstream product

• 2186-92-7 p-Anisaldehyde dimethyl acetal 
• 221149-02-6 4-allyl-8-trimethylsilanyl-5-(3-trimethylsilanyl-prop-2-ynyl)-oct-1-en-7-yne-4,5-diol 
• 38002-45-8 3-bromo-1-(trimethylsilyl)-1-propyne 
• 221149-01-5 2-hydroxy-5-trimethylsilanyl-2-(3-trimethylsilanyl-prop-2-ynyl)-pent-4-ynoic acid ethyl ester 

Downstream Products

• 221149-06-0 4,4-diallyl-2-(4-methoxy-phenyl)-5,5-di-prop-2-ynyl-[1,3]dioxolane 

Relevant academic research and scientific papers

Utility of the Tandem Pauson-Khand Reaction in the Construction of Tetracycles

The scope of the tandem Pauson-Khand reaction has been explored for the regiospecific construction of [5.5.5.5]- and [5.6.6.5]tetracyclic systems via the photolytic method of Livinghouse. The rapid regiospecific entry into the two dicyclopentapentanoid systems 17 and 29 was accomplished from the key diene-diynes 11 and 19b. A photochemically mediated catalytic tandem Pauson-Khand cyclization was employed to prepare the parent ring systems of dicyclopenta[a,e]pentalene (from 19b) and dicyclopenta[a,f]pentalene (from 11) in regiospecific fashion in a one-pot process. Under these conditions, conversion of acyclic diene-diyne 16 into tetracyclic system 17 was achieved in 74% yield, while a similar process was employed to convert 28 into tetracycle 29 in 90% yield. This is much improved over the previous conditions that employed NMO. Six carbon-carbon bonds were generated in this process constituting up to 98% yield for each carbon-carbon bond so formed. Furthermore, tetracyclic [5.6.6.5] systems such as dicyclopenta[b,g]decalins 37, 38, and 40 were prepared from similar diene-diyne precursors via the tandem Pauson-Khand cyclization. Importantly, acetal 36 provided the desired cis-fused [5.6.6.5] system 38a (via 40a/b) in stereospecific fashion. This reaction is unique in that it provides a cis-decalin ring system; moreover, the yield of each of the six carbon-carbon bonds formed in this process was at least 89%. The structure of cis diol 38a was confirmed by X-ray crystallography.

Extension of the tandem Pauson-Khand reaction to [5.6.6.5]Tetracycles: A unique entry into cis-fused decalins

The tandem Pauson-Khand reaction has been extended to the synthesis of [5.6.6.5]dicyclopenta[b,g]decalins. This approach provides a unique entry into a cis-fused decalin-based ring system via an acyclic precursor.