On the reaction of acetoacetic ester with (+)-carvone: An oxabicyclo[3.3.1]nonene and some bicyclo[3.3.1]nonanolones

Different routes for the construction of biologically active diversely functionalized bicyclo[3.3.1]nonanes: an exploration of new perspectives for anticancer chemotherapeutics

“…Cyclohexanones (72), when reacted in this manner with a,bunsaturated aldehydes or ketones (73), yield a bicyclo[3.3.1] nonane (74) with a ketone functionality at the bridgehead position (Scheme 8). 71 Similarly, Tückmantel and coworkers showed that b-keto ester (75) could also be annulated with acrolein (76) in the presence of a catalytic amount of TMG (1,1,3,3-tetramethylguanidine) to obtain the bicycle 77 (Scheme 9).…”

Natural cyclic α, β-enone monoterpenoids in nucleophilic addition reactions

“…Monoterpenoids with an enone system in their structure have been recommended as good Michael acceptors that bind nucleophiles in the β-position relative to the carbonyl [64][65][66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82]. The Michael reaction is a rather common method of forming C-C bonds.…”

“…Thus, the reaction of (S)-1 and acetoacetic ester in the presence of catalytic amounts of EtONa at 20°C produced enol monoacetal 162, treatment of which with aqueous base gave the aldol condensation product, which was a mixture of isomeric bicyclic hydroxyketones 163 and 164 [64]. If the Michael reaction was carried out at 80°C in the presence of stoichiometric amounts of base, these were formed in one step.…”

Mechanism and origin of stereoselectivity in Robinson annulations leading to bicyclo[3.3.1]nonanes: a rare Curtin–Hammet scenario

“…In particular, the subtle differences in reaction pathways leading to the formation of two diastereomeric products, with a preponderance of the anti products, are unclear. Indeed, previous literature adversely misassigned the stereocenter based on an otherwise logical thinking of the mechanism . Therefore, an in‐depth understanding of the potential energy surface, geometry of the intermediates and transition states, and stereochemistry in the reaction would be highly desirable.…”