New syntheses and potential antimalarial activities of new 'retinoid-like chalcones'

A series of 'retinoid-like chalcones' and diverse derivatives relative to licochalcone A were synthesized from a new enaminone synthon. These syntheses occurred via a new aromatic annelation. These new derivatives have been tested in vitro as potential antimalarial agents. The 4-hydroxy-chalcone-like (compound 6a, derived from beta-ionone) exhibits a good and reproducible inhibitory effect on the in vitro culture of Plasmodium falciparum, with an IC 50 lower than 10 microM for inhibition of 3H-hypoxanthine uptake by parasites (respectively, 4.93 and 8.47 microM for strains K1 and Thaï).

The effects of a novel synthetic retinoid, seletinoid G, on the expression of extracellular matrix proteins in aged human skin in vivo

BACKGROUND

Although retinoids have potential efficacy in aged skin, their side effect (skin irritation) remains a clinical problem. We designed a novel synthetic retinoid, seletinoid G, by using computer-aided molecular modeling, and investigated its effects on the expression of extracellular matrix proteins in human skin in vivo.

METHODS

Twenty-three subjects were tested on the buttocks using 4-day occlusive application of seletinoid G and all-trans retinoic acid (tRA). Skin irritation after topical application was quantified by the degree of erythema and cutaneous blood flow. The expression of extracellular matrix proteins and interstitial collagenase (MMP-1) in skin biopsies was investigated by immunohistochemical staining and Western blotting.

RESULTS

The topical application of seletinoid G under occlusion induced no skin irritation in contrast to tRA, which caused severe erythema. The topical treatment with seletinoid G increased the expressions of type I procollagen, tropoelastin, and fibrillin-1, and reduced MMP-1 in old skin in vivo. Seletinoid G was found to inhibit not only the UV-induced decrease of type I procollagen but the UV-induced increase of MMP-1 and c-Jun protein in young skin in vivo.

CONCLUSIONS

Seletinoid G is a novel synthetic retinoid, which has little the side effect of skin irritation after topical application. Seletinoid G can repair altered connective tissue in old skin and inhibit UV-induced collagen deficiency in young skin.

Synthesis and Structure−Activity Relationships of a New Series of Retinoid-Related Biphenyl-4-ylacrylic Acids Endowed with Antiproliferative and Proapoptotic Activity

Atypical retinoids (AR) represent a class of proapoptotic agents with promising potential in the treatment of neoplastic diseases. In the present work 4'-hydroxybiphenyl-4-ylacrylic acids were studied as a novel series of AR. The synthesized compounds were evaluated for their antiproliferative activity in a human promyelocytic leukemia cell line (NB4) and in an ovarian carcinoma cell system including IGROV-1, carrying a functional wild-type p53, and a cisplatin-resistant subline, IGROV-1/Pt-1. The presence of a bulky lipophilic group at position 3' (adamantan-1-yl being the best) and the E configuration of the acrylic moiety appear essential for activity below 1 muM. No substitution on the rings or on the double bond improved the activity. A qualitative correlation between the log P and molecular volume of the 3'-substituent and the antiproliferative activity was found. From the study of a few selected compounds, it appears that the presence of the carboxylic group is an essential requirement for apoptogenic properties but not for antiproliferative activity, this being maintained in amide derivatives. On the other hand, compounds able to induce apoptosis produced a detectable level of genotoxic damage. This observation supports the hypothesis that the genotoxic stress is a critical event mediating apoptosis induction by compounds of this class. Among the compounds investigated, E-3-(3'-adamantan-1-yl-4'-hydroxybiphenyl-4-yl)acrylic acid (2) was chosen for further investigation.

Studies on the Apoptotic Activity of Natural and Synthetic Retinoids: Discovery of a New Class of Synthetic Terphenyls That Potently Support Cell Growth and Inhibit Apoptosis in Neuronal and HL-60 Cells

New terphenyl derivatives have been synthesized and tested for their effect on cell survival in serum-free cultures. These compounds protected HL60 cells from death and supported their growth with an activity higher than that of the natural 14-hydroxy-retro-retinol. Terphenyls 26 and 28 also possess antiapoptotic activity on neuronal cells, proving them as possible candidates for the treatment of neurodegenerative and ischemic diseases.

Retinoids: potential in cancer prevention and therapy

Retinoids (derivatives of vitamin A) are signalling molecules that play important roles in cell growth, differentiation and death. Retinoids act through two types of receptors – retinoic acid receptors (RARα, RARβ and RARγ) and retinoid X receptors (RXRα, RXRβ and RXRγ) – which themselves act as ligand-dependent transcription factors. Retinoids are of special interest in cancer research owing to their antiproliferative and cancer-preventative properties. They have been used successfully to cure acute promyelocytic leukaemia (APL) and can suppress carcinogenesis in a variety of tissue types (e.g. skin, lung, breast and oral cancers). Extensive research efforts have been dedicated to elucidating the molecular and cellular networks that are induced by retinoids, and this has recently yielded novel insights into how retinoids can both prevent and combat cancer.

Synthesis of ring-oxidized retinoids as substrates of mouse class I alcohol dehydrogenase (ADH1)

Ring-oxidized retinoids have been synthesized stereoselectively using the Stille cross-coupling reaction. Kinetic constants of mouse class I alcohol dehydrogenase (ADH1) with these retinoids were determined.

Determinants of Retinoid X Receptor Transcriptional Antagonism

The synthesis and bioactivity of the retinoid X receptor (RXR) antagonist 4-[(3'-n-butyl-5',6',7',8'-tetrahydro-5',5',8',8'-tetramethyl-2'-naphthalenyl)(cyclopropylidene)methyl]benzoic acid and several heteroatom-substituted analogues are described. Ligand design was based on the scaffold of the 3'-methyl RXR-selective agonist analogue and reports that 3'-n-propyl and longer n-alkyl groups conferred RXR antagonism. The transcriptional antagonism of the 3'-n-butyl analogue was demonstrated by its blockade of retinoic acid receptor (RAR) beta expression induced by the RXRalpha/peroxisome proliferator-activated receptor (PPAR) gamma heterodimer complexed with an RXRalpha agonist plus the PPARgamma agonist ciglitazone and the inhibition of 9-cis-RA-induced coactivator SRC-1a recruitment to RXRalpha. Receptor-ligand docking studies using full-atom flexible ligand and flexible receptor suggested that binding of the antagonist to the RXRalpha antagonist conformation was favored because the salt bridge that formed between the retinoid carboxylate and the RXRalpha helix H5 arginine-321 was far stronger than that formed on its binding to the agonist conformation. The antagonist also blocked activation of RAR subtypes alpha and beta by 9-cis-RA but not that of RARgamma.

Differential expression of heparin-binding EGF-like growth factor (HB-EGF) mRNA in normal human keratinocytes induced by a variety of natural and synthetic retinoids

It was recently revealed that epidermal growth following topical treatment with all-trans retinoic acid (atRA) was at least partly induced by heparin-binding epidermal growth factor-like growth factor (HB-EGF) released from suprabasal keratinocytes. Since proliferation of keratinocytes appears to be one of the critical roles of atRA in depigmentation treatment and promotion of wound healing, HB-EGF is considered suitable for assessing the therapeutic value of topical retinoids. In this study, HB-EGF mRNA expression in normal human keratinocytes after atRA treatment was examined, and the effects of a variety of natural and synthetic retinoids were compared. The results of reverse transcription polymerase chain reaction (RT-PCR) suggested that induction of differentiation increased HB-EGF mRNA expression in cultured keratinocytes. Real-time PCR analyses revealed that HB-EGF mRNA expression was elevated dose-dependently with atRA, peaking at 12 h. This elevation was more prominent in confluent keratinocytes than in subconfluent cells, suggesting that differentiated keratinocytes are more subject to stimulation of HB-EGF expression by atRA than proliferating keratinocytes. HB-EGF mRNA was upregulated in differentiation-induced keratinocytes by all retinoids used in this study at 1 micromol/l, and marked upregulation was seen when treated with three isotypes of retinoic acid (atRA, and 9-cis and 13-cis retinoic acid). RARalpha-selective agonists (Am80, Am580, ER-38925, and TAC-101) and a panagonist of RARs (Re80) caused relatively low elevation of HB-EGF transcripts, as did all-trans retinol (Rol) and all-trans retinal (Ral). Although another panagonist (Ch55) showed the highest elevation of HB-EGF mRNA, it was relatively cytotoxic at the concentration employed. Ral and Rol were found to upregulate HB-EGF when used at 100 micromol/l to 1 mmol/l, to a similar extent of atRA at 1-10 micromol/l. The capacity of retinoids to upregulate HB-EGF may be an important index for investigation and development of an ideal synthetic retinoid, which has maximum benefits and minimum side-effects

Synthesis of flexible sulfur-containing heteroarotinoids that induce apoptosis and reactive oxygen species with discrimination between malignant and benign cells

Regulation of growth, differentiation, and apoptosis by synthetic retinoids can occur through mechanisms that are dependent and independent of their ability to bind and activate nuclear retinoic acid receptors. The objective of this study was to determine if increasing flexibility of the heteroarotinoid structure would affect the specificity of the synthetic retinoids for the receptors and for their regulation of cancerous and nonmalignant cells. Methods were developed to produce the first examples of heteroarotinoids 15a-15h, which contain urea and/or thiourea linking groups between two aryl rings. Substituents at the para position of the single phenyl ring were either an ester, a nitro group, or a sulfonamide group. Ovarian cancer cell lines Caov-3, OVCAR-3, SK-OV-3, UCI-101, and 222 were utilized, and the inhibitory prowess of the heteroarotinoids was referenced to that of 4-HPR (25). Similar to 4-HPR (25), the heteroarotinoids inhibited growth of all cell lines at micromolar concentrations. Although the heteroarotinoids did not activate retinoic acid receptors, the agents induced potent growth inhibition against the cancer cells with weak activity against normal and benign cells. The growth inhibition was associated with cell loss and induction of reactive oxygen species.

Novel Heteroarotinoids as Potential Antagonists of Mycobacterium bovis BCG

A series of 15 heteroarotinoids has been prepared and evaluated for activity against Mycobacterium bovis BCG with the thiourea-containing isoxyl (7) (0.5 microg/mL) as the standard. 2,2,4-Trimethyl-2H-chromen-7-yl 4-(methoxycarbonyl)benzoate (8) displayed the most significant activity (2.0-4.0 microg/mL) in terms of the lowest concentration (microg/mL) (MIC, minimum inhibitory concentration) required to produce a 99% reduction in the number of colonies on a plate as compared to that system free of the agent at the same dilution of the culture suspension. Ethyl 4-[[N-(2,2,4,4-tetramethylchroman-6-yl)thiocarbamoyl]amino]benzoate (9) and [[(1E,3Z,5E)-1-aza-4-methyl-6-(1,2,2,4-tetramethyl(1,2-dihydroquinolyl))hexa-1,3,5-trienyl]amino]aminomethane-1-thione (10) exhibited activity at 5.0-10.0 and 10.0-20.0 microg/mL, respectively, while the other examples had MIC values of 20 microg/mL or greater. The inhibitory ability of 8 may occur via the inhibition of mycolic acid synthesis in a like manner as found with 7, but this requires further study. The heteroarotinoids are the first examples to exhibit inhibitory ability against the growth of Mycobacterium bovis BCB.

Differential regulation of protein expression, growth and apoptosis by natural and synthetic retinoids

All-trans retinoic acid (ATRA) can down regulate the anti-apoptotic protein Bcl-2 and the cell cycle proteins cyclin D1 and cdk2 in estrogen receptor-positive breast cancer cells. We show here that retinoids can also reduce expression of the inhibitor of apoptosis protein, survivin. Here we have compared the regulation of these proteins in MCF-7 and ZR-75 breast cancer cells by natural and synthetic retinoids selective for the RA receptors (RARs) alpha, beta, and gamma then correlated these with growth inhibition, induction of apoptosis and chemosensitization to Taxol. In both cell lines ATRA and 9-cis RA induced the most profound decreases in cyclin D1 and cdk2 expression and also mediated the largest growth inhibition. The RARalpha agonist, Ro 40-6055 also strongly downregulated these proteins although did not produce an equivalent decrease in S-phase cells. Only ATRA induced RARbeta expression. ATRA, 9-cis RA and 4-HPR initiated the highest level of apoptosis as determined by mitochondrial Bax translocation, while only ATRA and 9-cis RA strongly reduced Bcl-2 and survivin protein expression. Enumeration of dead cells over 96 h correlated well with downregulation of both survivin and Bcl-2. Simultaneous retinoid-mediated reduction of both these proteins also predicted optimal Taxol sensitization. 4-HPR was much weaker than the natural retinoids with respect to Taxol sensitization, consistent with the proposed requirement for reduced Bcl-2 in this synergy. Neither the extent of cell cycle protein regulation nor AP-1 inhibition fully predicted the antiproliferative effect of the synthetic retinoids suggesting that growth inhibition requires regulation of a spectrum of RAR-regulated gene products in addition even to pivotal cell cycle proteins.

Design and synthesis of fluorinated RXR modulators

Fluorinated trienoic acid analogues of the RXR selective modulator 1 (LG101506) were synthesized, and tested for their ability to bind RXRalpha and activate RXR homo and heterodimers. Potency and efficacy were observed to be dependent upon the position of fluorination, and improvement in pharmacological profile was demonstrated in some cases.

The synthetic heteroarotinoid SHetA2 induces apoptosis in squamous carcinoma cells through a receptor-independent and mitochondria-dependent pathway

Retinoids that regulate cell growth, differentiation, and apoptosis have shown promising results in preclinical studies and in a few clinical trials of cancer chemoprevention and therapy. However, the clinical use of retinoids is limited by resistance of certain malignant cells to their antitumor effects and by side effects. To identify more potent retinoids, we examined the effects of heteroarotinoids (Hets), new synthetic retinoids with reduced toxicity, on the growth of human head and neck squamous cell carcinoma (HNSCC) lines. Six Hets with different retinoic acid receptor activation potentials were found to exhibit distinct efficacies. The most potent among the Hets examined, SHetA2, [[(4-nitrophenyl)amino][2,2,4,4-tetramethyl thiochroman-6-yl)amino] methane-1-thione], was more effective than either all-trans- or 9-cis-RA. The growth of UMSCC38, the most sensitive among the eight HNSCC cell lines examined, was suppressed by ShetA2 in a dose- and time-dependent fashion. SHetA2-induced apoptosis in UMSCC38 cells was comparable with N-(4-hydroxyphenyl)retinamide (4HPR). Reactive oxygen species (ROS) generation in the UMSCC38 cells was increased by SHetA2, and this effect was suppressed by the antioxidant butylated hydroxyanisol, which also suppressed SHetA2-induced apoptosis. SHetA2 suppressed mitochondrial permeability transition and enhanced cytochrome c release from mitochondria. Both of these effects were prevented by cyclosporin A, which also decreased SHetA2-induced apoptosis. SHetA2 increased caspase-3-like activity, and a caspase-3 inhibitor diminished SHetA2-induced apoptosis. Several retinoid receptor antagonists failed to prevent apoptosis induction by SHetA2. These results demonstrate that SHetA2 is a potent, receptor-independent, apoptosis inducer that acts on the mitochondria in HNSCC cells. Further investigation of the potential of SHetA2 in prevention and therapy of HNSCC is warranted also because of much lower toxicities compared with receptor active retinoids.

A novel atypical retinoid endowed with proapoptotic and antitumor activity

The novel atypical retinoid E-3-(4'-hydroxy-3'-adamantylbiphenyl-4-yl)acrylic acid (ST1926, 4) exhibited a potent antiproliferative activity on a large panel of human tumor cells. Despite almost complete loss of ability to activate RARs, the compound was an effective apoptosis inducer and surprisingly produced DNA damage, that likely contributes to the proapoptotic activity. Following oral administration, 4 was well tolerated and caused tumor growth inhibition in the ovarian carcinoma, A2780/DX, and in the human melanoma, MeWo, growing in nude mice, thus supporting the therapeutic interest of the novel agent.

Retinoids as chemopreventive agents

Retinoids are promising agents for cancer chemoprevention. The myriad effects of retinoids on biological processes including development, differentiation, homeostasis, carcinogenesis and apoptosis are mediated through their molecular targets, the retinoid and rexinoid receptors. Tissue specific expression patterns, ligand specificities, receptor numbers, their distinct functions and functional redundancy make retinoid signaling highly complex. The cross-talks of these receptors with cell surface receptors signaling pathways, as well as their interactions with multiple co-activators and co-repressors further add to the complexity of the pleiotropic effects of retinoids. Elucidation of retinoid signaling pathways and indepth understanding of the mechanisms that underlie the anti-proliferative and apoptotic action of retinoids has paved the way for designing synthetic retinoids for effective chemoprevention and therapy of cancer. Development of receptor selective synthetic retinoids is a major focus of molecular retinoid development. Other new avenues encompass identification of novel retinoid regulated genes, orphan-receptor ligands/functions, novel retinoid mechanisms involving receptor-independent apoptosis inducing activity and synergistic combinations with other agents for cancer prevention and therapy. This review focuses on recent advances in the understanding of molecular mechanisms underlying the action of retinoids and retinoid molecular targeting studies designed primarily to develop retinoids with reduced toxicity, while maintaining or enhancing activity in context of chemoprevention. The clinical efficacy of retinoid based chemoprevention trials is discussed.

Synthesis and biological activity of retinoic acid receptor-alpha specific amides

Retinoids are analogues of all-trans-retinoic acid, a powerful hormone that mediates many fundamental biological processes. Cancer and other serious hyperproliferative diseases are attractive therapeutic targets for retinoids, but the therapeutic use of retinoids is limited due to severe toxicity. We report here the design of retinoid receptor-alpha specific ligands with growth inhibitory activity in breast cancer cell lines, and which do not cause the cutaneous toxicity associated with the currently available nonselective retinoid agonists.

An improved synthesis of the C-linked glucuronide of N-(4-hydroxyphenyl)retinamide

Retinoic acid analogues such as N-(4-hydroxyphenyl)retinamide (4-HPR) are effective chemopreventatives and chemotherapeutics for numerous types of cancer. The C-linked analogue of the O-glucuronide of 4-HPR (4-HPRCG) has been shown to be a more effective agent. The synthetic route to this molecule has been significantly improved by access to a key C-benzyl-glucuronide intermediate through employment of a Suzuki coupling reaction between an exoanomeric methylene sugar and an aryl bromide. Preliminary evidence shows 4-HPRCG has chemotherapeutic activity.

Synthesis and antioxidative properties of novel thiazolidinedione/imidazolidinedione compounds as retinoids

The general term "retinoids" refers to both naturally occurring as well as synthetic compounds which exhibit biological activity similar to vitamin A (retinol). Vitamin A and its two metabolites, retinaldehyde and retinoic acid, are fat-soluble unsaturated isoprenoids necessary for the growth, differentiation and maintenance of epithelial tissues. In this study, we have synthesized thiazolidinedione/imidazolidinedione compounds as retinoids. Their in vitro effects on rat liver microsomal NADPH-dependent lipid peroxidation (LP) levels and superoxide anion formation were determined.

Selective alteration of gene expression in response to natural and synthetic retinoids

BACKGROUND

Retinoids are very potent inducers of cellular differentiation and apoptosis, and are efficient anti-tumoral agents. Synthetic retinoids are designed to restrict their toxicity and side effects, mostly by increasing their selectivity toward each isotype of retinoic acids receptors (RARalpha,beta, gamma and RXRalpha, beta, gamma). We however previously showed that retinoids displayed very different abilities to activate retinoid-inducible reporter genes, and that these differential properties were correlated to the ability of a given ligand to promote SRC-1 recruitment by DNA-bound RXR:RAR heterodimers. This suggested that gene-selective modulation could be achieved by structurally distinct retinoids.

RESULTS

Using the differential display mRNA technique, we identified several genes on the basis of their differential induction by natural or synthetic retinoids in human cervix adenocarcinoma cells. Furthermore, this differential ability to regulate promoter activities was also observed in murine P19 cells for the RARbeta2 and CRABPII gene, showing conclusively that retinoid structure has a dramatic impact on the regulation of endogenous genes.

CONCLUSIONS

Our findings therefore show that some degree of selective induction or repression of gene expression may be achieved when using appropriately designed ligands for retinoic acid receptors, extending the concept of selective modulators from estrogen and peroxisome proliferator activated receptors to the class of retinoid receptors.

Receptor selective synthetic retinoids as potential cancer chemotherapy agents

For many years, the vitamin A metabolite retinoic acid (RA) has been known to have profound effects on development, cellular proliferation and differentiation, and tumor growth and invasion. The wide-ranging effects of RA on cellular proliferation and migration have made it a useful chemotherapeutic agent in the treatment of many types of cancer. In the last fifteen years, with the discovery of nuclear receptors for RA, the molecular basis for the effects of this molecule has become apparent. Retinoic acid receptors (RAR) are members of a superfamily of ligand dependent transcription factors that interact with an increasingly large array of coactivators and repressors to regulate target gene expression through binding to cognate recognition sequences in the promoters of these genes. Alterations in RAR expression and function have been demonstrated in many types of cancer. The translocation of RARalpha with PML or PLZF genes in acute promyelocytic leukemia is a paradigm of the role of RARs in cancer biology. In addition, the development of receptor selective synthetic retinoids has greatly expanded our knowledge of RAR function in tumor cells and provided additional treatment options for cancer patients. This review will examine the development of receptor selective retinoids, their uses to date, and future potential.

Effect of natural and synthetic retinoids on the proliferation and differentiation of three canine melanoma cell lines

The effect of two natural retinoids and synthetic retinoids with or without retinoid synergists on the proliferation and differentiation of 3 melanoma cell lines were investigated in vitro. No retinoids showed significant growth inhibitory effect on these cell lines when used alone, however, cell differentiation and significant growth inhibition were observed when treated with a combination of retinoids and a retinoid synergist. This study may suggest that, though the cells showed low susceptibilities when retinoids were treated alone, the combination of retinoids and a retinoid synergist may be effective to control the growth of canine melanoma cell lines.

Unique property of some synthetic retinoids: activation of the aryl hydrocarbon receptor pathway

Potential pharmacological applications in the areas of oncology, dermatology, diabetes, and atherosclerosis of synthetic analogs of retinoic acid that target a specific nuclear receptor and/or biological response have generated great interest in the development of new retinoid and rexinoid drugs. The pan-retinoic acid receptor antagonist AGN 193109 has been previously reported to elevate CYP1A1 levels, implicating the aryl hydrocarbon receptor (AhR) as an additional target for this retinoid. AhR is a cytosolic ligand-dependent transcription factor that, in conjunction with the AhR nuclear translocator (Arnt), binds to dioxin response elements (DREs) located in the promoter region of target genes, such as CYP1A1, and induces their transcription. The purpose of these studies was to determine whether additional synthetic retinoids were capable of elevating CYP1A1 levels and to examine the mechanism of this increase in CYP1A. Two additional retinoids, AGN 190730 and AGN 192837, were found to be potent inducers of DRE-driven transcriptional activity; AGN 190730 was the most potent. Moreover, electrophoretic mobility-shift assays demonstrate that AGN 190730 can transform AhR into its active DNA recognition form. In addition, trypsin digestion of AGN 190730-treated AhR reveals a conformational change in the protein similar to the conformational change of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-bound AhR. Finally, competitive binding studies demonstrate that AGN 190730 can inhibit the binding of TCDD to AhR. The sum of the data demonstrates that some synthetic retinoids in addition to activating the retinoic acid receptor/retinoid X receptor pathway are capable of binding to AhR and activating the AhR/Arnt pathway.

Synthesis of novel retinoid X receptor-selective retinoids

Retinoids 1-5 have been identified as potent RXR agonists for evaluation in the treatment of non-insulin-dependent (type II) diabetes mellitus (NIDDM). Highly convergent syntheses of 1-5 have been developed. The core tetrahydronaphthalene 7, employed in the synthesis of 1 and 2, was prepared in 98% yield using an AlCl(3)-catalyzed (0.03 equiv) Friedel-Crafts alkylation of toluene with 2,5-dichloro-2,5-dimethylhexane 6. A nitromethane-mediated Fridel-Crafts acylation of 7 with chloromethylnicotinate 9 was developed to prepare ketone 10 in 68% yield. Chelate-controlled addition of MeMgCl to 10 followed by dehydration afforded olefin 11 in 65% yield. Cyclopropanation of 11 with trimethylsulfoxonium ylide, followed by saponification, completed a five-step synthesis of 1 in 33% yield. FeCl(3)-catalyzed (0.05 equiv) Friedel-Crafts acylation of 7 with chloromethylterephthalate 14 afforded ketone 15 in 81% yield. Saponification of 15 and reaction with 50% aqueous NH(2)OH in AcOH afforded a 9:1 mixture of cis and trans oximes, from which the desired cis-oxime 2 was isolated in 43% yield. The core bromo-dihydronaphthalene 29 required for the synthesis of 3-5 was prepared by a Shapiro reaction. Transmetalation of 29 and reaction with Weinreb amides 30b or 36 afforded ketones 32 and 37, which were converted into 3-5 using chemistry comparable to the tetrahydronaphthylene series. Suzuki coupling of boronic acids 41 and 42 with vinyl triflate 43 provided an alternative approach to the synthesis of this class of compounds.