95687-90-4Relevant articles and documents
Probing competitive and co-operative hydroxyl and ammonium hydrogen-bonding directed epoxidations
Brambilla, Marta,Brennan, Méabh B.,Csatayová, Kristína,Davies, Stephen G.,Fletcher, Ai M.,Kennett, Alice M.R.,Lee, James A.,Roberts, Paul M.,Russell, Angela J.,Thomson, James E.
, p. 10297 - 10309 (2018/05/31)
The diastereoselectivities and rates of epoxidation (upon treatment with Cl3CCO2H then m-CPBA) of a range of cis- and trans-4- aminocycloalk-2-en-1-ol derivatives (containing five-, six-, and seven-membered rings) have been investigated. In all cases where the two potential directing groups can promote epoxidation on opposite faces of the ring scaffold, evidence of competitive epoxidation pathways, promoted by hydrogen-bonding to either the in situ formed ammonium moiety or the hydroxyl group, was observed. In contrast to the relative directing group abilities already established for the sixmembered ring system (NHBn ? OH > NBn2), an N,N-dibenzylammonium moiety appeared more proficient than a hydroxyl group at directing the stereochemical course of the epoxidation reaction in a five- or seven-membered system. In the former case, this was rationalized by the drive to minimize torsional strain in the transition state being coupled with assistance from hydrogenbonding to the ammonium moiety. In the latter case, this was ascribed to the steric bulk of the ammonium moiety disfavoring conformations in which hydrogen-bonding to the hydroxyl group results in direction of the epoxidation to the syn face. In cases where the two potential directing groups can promote epoxidation on the same face of the ring scaffold, an enhancement of epoxidation diastereoselectivity was not observed, while introduction of a second, allylic heteroatom to the substrate results in diminishment of the rate of epoxidation in all cases. Presumably, reduction of the nucleophilicity of the olefin by the second, inductively electron-withdrawing heteroatom is the dominant factor, and any assistance to the epoxidation reaction by the potential to form hydrogen-bonds to two directing groups rather than one is clearly unable to overwhelm it.
A SIMPLE APPROACH TO NORTROPANE AND NORTROP-6-ENE DERIVATES
Bathgate, Antoinette,Malpass, John R.
, p. 5937 - 5940 (2007/10/02)
Intramolecular cyclisation of trans-1-(benzylamino)-4-chlorocycloheptane and hept-2-ene gives the corresponding 8-azabicyclo(3.2.1)octane (nortropane) and -oct-6-ene (nortrop-6-ene) derivatives respectively.Under appropriate conditions, cyclohept-1,3-diene is converted into nortropane in 75percent overall yield.
A NEW SYNTHETIC ROUTE TO TROPANE ALKALOIDS. PSEUDOTROPINE AND TROPACOCAINE
Iida, Hideo,Watanabe, Yohya,Kibayashi, Chihiro
, p. 5091 - 5094 (2007/10/02)
Pseudotropine and tropacocaine have been synthesized by a facile route involving the nitroso cycloaddition followed by internal SN2 displacement.
