Solvolysis of 5-brexyl brosylates: Relevance to carbene and carbocation chemistry

Formation of synthetically useful camphor derivatives: mechanistic aspects

“…Subsequent brornination ( l c ) then provided the corresponding 3,3-dibromo derivatives. The almost exclusive occurrence of 3,2-exo rather than 3,2-endo methyl shifts in rearrangements involving bornyl or norbornyl carbocations has been thoroughly documented by several research groups (9)(10)(11)(12)(13)(14)(15)(16)(17), and a stereoelectronic effect (8,20,21) has been proposed to account for this stereoselectivity. The stereoelectronic effect can be illustrated in the case of camphene (47) racemization (cf.…”

Non‐canonical Biosynthesis of the Brexane‐Type Bishomosesquiterpene Chlororaphen through Two Consecutive Methylation Steps in Pseudomonas chlororaphis O6 and Variovorax boronicumulans PHE5‐4

“…These data revealed a helical tricyclo[4.3.0.0 3.7 ]nonane skeleton comprised of two partially superimposed norbornyl units known as brexane (in reference to the bridge involving an exo‐norbornyl bond) [13] . Brexanes have previously been explored as models for non‐classical carbocations, [14–21] but have never been observed as natural products. The 5‐ethyl‐2‐methylene‐1,3,4,6,7‐pentamethylbrexane skeleton of chlororaphen ( 6 ) corresponds to an EIMS fragmentation pattern that shows characteristic fragment ions at m / z 150 for C 11 H 18 from neutral loss of C 6 H 10 , and m / z 122 for C 9 H 14 from neutral loss of C 8 H 14 (Figure 3a).…”

“…These data revealed a helical tricyclo[4.3.0.0 3.7 ]nonane skeleton comprised of two partially superimposed norbornyl units known as brexane (in reference to the bridge involving an exo-norbornyl bond). [13] Brexanes have previously been explored as models for nonclassical carbocations, [14][15][16][17][18][19][20][21] but have never been observed as natural products.…”