The Baylis-Hillman reaction, the coupling of an unsaturated carbonyl compound/nitrile with aldehydes, is a valuable reaction but is limited in its practicality by poor reaction rates. We have endeavored to accelerate the reaction using Lewis acids and found that while conventional Lewis acids gave reduced rates group III, and lanthanide triflates (5 mol %) gave increased rates. The optimum metal salts were La(OTf)(3) and Sm(OTf)(3), which gave rate accelerations (k(rel)) of approximately 4.7 and 4.9, respectively, in reactions between tert-butyl acrylate and benzaldehyde when using stoichiometric amounts of DABCO. At low loadings of DABCO (up to 10 mol %), no reaction occurred due to association of DABCO with the metal. Use of additional ligands to displace the DABCO from the metal was studied, and the rate of reaction was found to increase further in most cases. Of the ligands tested, at 5 mol %, (+)-binol gave one of the largest rate accelerations (3.4-fold) and was studied in more detail. It was found that reactions occurred even at low DABCO concentration so that here the Lewis base and Lewis acid were able to promote the reaction without interference from each other. While the (+)-binol (and other chiral ligands) failed to provide any significant asymmetric induction, a substantial nonlinear effect was observed with binol. Thus, use of racemic binol gave no effect on the rate. In seeking to maximize the rate attainable, more soluble (liquid) ligands were studied. Diethyl tartrate and triethanolamine gave rate enhancements of 5.2x and 3.5x at 50 mol %, respectively, versus 1.5x and 2.3x at 5 mol %. The best protocol was to use 100 mol % DABCO, 50 mol % triethanolamine, and 5 mol % La(OTf)(3). This gave overall rate accelerations of between 23-fold and 40-fold depending on the acrylate and approximately 5-fold for acrylonitrile. A simple acid wash removed the reagents, leaving the product in the organic phase. While triethanolamine accelerated the reaction without the lanthanum triflate (18-22-fold at 80 mol %), the reaction in the presence of the metal salt was faster. The system was tested synthetically on various substrates and found to give good rate accelerations with both activated (benzaldehyde and p-nitrobenzaldehyde) and less activated aldehydes (anisaldehyde and cyclohexanecarboxaldehyde) with acrylates. The limited amount of dimerized acrylate in the latter reactions is noteworthy and should extend the range of substrates that can be made by the Baylis-Hillman reaction using our optimum conditions.

A range of tamoxifen derivatives substituted in the 4-position of the 1-phenyl ring are described. The key steps in the synthesis of 4-iodo-, 4-bromo-, and 4-(methylthio)tamoxifen were reactions of 1,2-diarylbutanones with the (4-halogenophenyl)lithium or [4-(methylthio)phenyl]magnesium bromide. Oxidized precursors of 4-(methylthio)tamoxifen were used to prepare the methylsulfinyl and methylsulfonyl derivatives. Further derivatives (formyl, hydroxymethyl, oxirane, mercapto) were prepared from 4-bromotamoxifen via the 4-lithio derivative. Several of the derivatives (Br, I, SMe, SOMe, SO2Me, oxirane, CHO, CH2OH) displayed a higher affinity for estrogen receptors (ER) of calf uterine cytosol than did tamoxifen, but there was no relationship between affinity to ER and the ability to inhibit the growth of the MCF-7 breast cancer cell line in vitro.

A mechanism for the generation of electrophilic alkylating agents from tamoxifen by hepatic alpha-oxidation of its ethyl group is presented which accounts for the formation of covalent DNA adducts associated with its hepatic carcinogenicity. The key process leading to the generation of electrophilic alkylating agents from tamoxifen is postulated to be alpha-hydroxylation in conjunction with 4-hydroxylation or secondary metabolic conjugation. The mechanism explains the lack of DNA adducts observed for the tamoxifen analogues toremifene, droloxifene and idoxifene and accounts for the species variation in hepatic carcinogenicity of tamoxifen.

Esters of 3- and 4-pyridylacetic acid have been prepared and tested for inhibitory activity toward the human testicular 17 alpha-hydroxylase/C17,20-lyase and human placental aromatase enzymes. The structural features required for optimal inhibition of the hydroxylase/lyase enzyme were a 3-pyridine ring, methyl substitution alpha to the carbonyl group, and a bulky alkoxycarbonyl substituent. The compounds with the greatest selectivity were isopinocampheyl 2-methyl-2-(3-pyridyl)propanoate, 9, 1-adamantyl 2-methyl-2-(3-pyridyl)propanoate, 12, and 2-methyl-2-adamantyl 2-methyl-2-(3-pyridyl)propanoate, 14, which, while inhibiting the aromatase activity with IC50 values of 30, 35, and 40 microM, respectively, exhibited IC50 values toward hydroxylase/lyase of between 13 and 90 nM. For comparison, ketoconazole gave an IC50 value of 15 microM against aromatase and values of 65 and 26 nM for inhibition of the hydroxylase and lyase activities, respectively. Some of the structural features required for enzyme inhibition also conferred resistance to esterase hydrolysis, in vitro using rat liver microsomes as a source of the esterase activity. Therefore these esters are lead compounds in the development of inhibitors of androgen biosynthesis for the treatment of hormone-dependent prostatic cancer.

In the exploration of the structural features that affect the RBA (binding affinity for the estrogen receptor of rat uterus relative to that of estradiol) in the tamoxifen [trans-(Z)-1-[4-[2-(dimethylamino)ethoxy]phenyl ]-1,2-diphenyl-1-butene] series, several derivatives variously substituted in the 1-phenyl group have been synthesized. [In the tamoxifen series, the descriptors E and Z, which define the configuration of the geometrical isomers and depend on the location and nature of substituents in the aromatic moieties and the ethyl group, may vary, although the relative configuration (cis or trans) does not. In order to avoid confusion the terms cis and trans will be used in this paper to refer to the relative positions of the 4-[2-(dimethylamino)ethoxy]phenyl and ethyl (or hydroxyethyl, hydroxypropyl, or bromo) substituents attached to the ethene moiety.] The final stage of each synthesis involved acid-catalyzed dehydration of a tertiary alcohol, and, in contrast to the known 3- and 4-hydroxy derivatives which were obtained as near-equimolar cis,trans mixtures, only the trans forms of the 2-hydroxy, 2-methyl, 2,4-dihydroxy, and 4-hydroxy-2-methyl derivatives were obtained. Also, in contrast to the trans forms of the 3- and 4-hydroxy derivatives, which are readily equilibrated to cis,trans mixtures, the trans 2-hydroxy derivative could not be isomerized. Tamoxifen and 2-methyltamoxifen had similar RBA's (approximately 1% of that of E2), but that of 2-hydroxytamoxifen was much lower (0.1%). Introduction of a second hydroxyl group (2,4-dihydroxy derivative) enhanced the RBA, and for the 4-hydroxy-2-methyl derivative, the RBA and growth inhibitory activity against the MCF-7 mammary tumor cell line in vitro were high and comparable to those of 4-hydroxytamoxifen, a metabolite of the parent drug. Tamoxifen derivatives hydroxylated at positions 3 or 4 of the 1-butene moiety and the 5-hydroxy-1-pentene analogue were also synthesized, but they had very low RBA values.