Long-acting contraceptive agents: Norethisterone esters of arylcarboxylic acids

Identifying structural features on 1,1-diphenyl-hexahydro-oxazolo[3,4-a]pyrazin-3-ones critical for Neuropeptide S antagonist activity

“…Alternatively, 1a was coupled to a number of acids with benzotriazole-1-yl-oxy-tris-(dimethylamino)phosphonium hexafluorophosphate (BOP) in tetrahydrofuran to provide amides 1m-o. The N-alkyl amines 1p and 1q were prepared by reductive amination of 1a with 4-(4fluorophenyl)-butanal, which was obtained through oxidation of 4-(4-fluorophenyl)butanol 16 with pyridinium chlorochromate in dichloromethane, or formaldehyde using sodium triacetoxyborohydride in dichloroethane. 17 Target compounds were fully characterized by NMR and mass spectroscopy.…”

Using Benzotriazole Esters as a Strategy in the Esterification of Tertiary Alcohols

“…Norethisterone (23) belongs to the first generation of synthetic progestins; this compound is still widely employed as a contragestational agent as well as in hormone replacement therapy. 38 Additionally, it has been demonstrated that norethisterone induces in vitro transactivation of an estrogen-regulated reporter vector transiently cotransfected with the estrogen receptor a or estrogen receptor b in African green monkey kidney CV-1 cells. 39 In the case of the reaction of alcohol 23 with acetic acid (22), the yield of ester 24 was 93% when DMAP was used as the base and 90% with calcined hydrotalcite as the base (Table 4, entry 3).…”