A short synthesis of (±)-sativen

The Application of Cyclobutane Derivatives in Organic Synthesis

“…The mixture of two isomeric bromobicyclo[3.2.0]heptenones 263a and 263b yielded the ring enlarged ketone 264 upon treatment with the buta-1,2-dienyltitanium complex generated from 2-butyne, tert- butyllithium, and Ti(O i Pr) 4 in hexane at −80 °C, and subsequent hydrolysis. This multistep ring expansion involves an intramolecular Diels−Alder cycloaddition of an intermediate allene moiety and a cyclopentadiene leading to the tricyclic cyclopentanone 264 in 52% yield 91 …”

“…A range of palladium-catalyzed hetero-and carboannelation reactions involving cyclobutanes has been reported by Larock. 63,64 For example, in the course of the heteroannelation of isopropenylcyclobutane (125) to N-(2-iodophenyl)toluenesulfonamide (124) a 2-butenyl-substituted dihydro-1-tosylindole 126 was formed in 60% yield within 4 days at 100 °C. 64 With oxovanadium(V) derivatives as a one-electron oxidant, 6-chloro-1,3-diketones as well as 2-tetrahydrofuranylmethyl ketones are formed from 1-(1hydroxycyclobutyl)hexan-2-one (127) or other 1-(2'oxoalkyl)cyclobutanols.…”

Cyclobutane based “overbred intermediates” and their exploration in organic synthesis

“…In the final example, complex carbocyclic bridged skeleton 133 en route to sativene was constructed through the cleavage of the cyclobutane overbred intermediate 135 as shown below. 44 The initial cyclobutane 136 was accessed through olefin/ketene thermal [2 + 2] cycloaddition followed by nucleophilic addition generated from propargyl species leading to the allenyl-cyclobutane overbred skeleton 135 . Treatment with NBS triggered the cb overbred intermediate cleavage and the ensuing [4 + 2] cycloaddition led to the unique bridge skeleton (Scheme 23).…”

Lewis Acid Catalyzed Site‐Selective Cycloadditions of 2,6‐Diazasemibullvalenes with Isocyanides, Azides, and Diazo Compounds for the Synthesis of Diaza‐ and Triazabrexadiene Derivatives

“…[1] Brexanes (tricyclo[4.3.0.0 3,7 ] nonanes), brexadienes, and their aza analogues have structurally interesting cage architectures and are important intermediates for organic synthesis (Scheme 1). [2,3] However, efficient synthetic methods toward brexane derivatives and their aza analogues are very rare.…”

“…These reactions afforded 5,8-diaza-and 2,5,9-triazabrexadiene derivatives, having highly-fused nitrogen-containing polycyclic frameworks; these structurally and chemically interesting caged-shape compounds are not readily accessible by other methods. [2,3] Unique and unprecedented rearrangement/ cycloaddition pathways are revealed. These reaction pathways are not only different from that of our previously reported reaction with DMAD or RNCO, [6] but most notably, very different from the reactions of common aziridines, [7][8][9][10] because of the active involvement of the whole ring skeleton of the NSBV compound.…”