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A series of internal deletion mutants of the vitamin D receptor (VDR) hinge is generated and found that deletion of a few as five amino acids from the C-terminus of the hinge significantly reduces transcriptional activation in vivo. The ability to delete more of the RxR hinge may be related to the additional plasticity required by its role as the common hetereodimer partner for nuclear receptors on differing DNA elements.

A cyclic beta-ketoester is synthesized from the (R)- and (S)-citronellol, representing an enantioselective Ru-BINAP hydrogenation of cyclopentanone carboxylates. Research demonstrates that the beta-ketoester is useful in steroid total synthesis as exemplified by its conversion to secosteroid (-)-astrogorgiadiol.

Research has been conducted on the 1(alpha),25-dihydroxy vitamin D (sub)3. Results indicate the degradation of this vitamin (sub)3 in the vitamin D receptor.

The alkoxycarbonylation of the A-ring of 1alpha,25-dihydroxyvitamin D(sub)3 using Candida antarctica lipase displays regioselectivity of 95% or greater toward the C-5-(S) hydroxyl group. Analogues of vitamin D(sub)3 may be useful therapeutic agents.

Cyclopentenones attached to tetrahydropyran rings are the products of the intramolecular coupling of alkyne-cyclopropylcarbene-chromium complexes with a propargylic stereocenter in high stereoselectivity. The trans heterocycle is preferentially generated, which is explained by thermodynamic control during the reduction of a cyclopentadienone intermediate. These reaction processes are used for the synthesis of the Vitamin D precursor de-ABC-cholestan-14-one.

A very short synthetic route to 25-hydroxy vitamin D building blocks is described. The synthesis proceeded with the tandem conjugate addition of ketene acetals and two Michael-Mukaiyama acceptors. Stereoselective reduction of the carbonyl group and allylic formate hydrogenolysis led to the transformation of intermediate alpha,beta-unsaturated ketones into the corresponding trans-hydrindan derivatives.

A novel method of synthesizing 1alpha,25-dihyroxy vitamin D3 was developed through manipulation of cross-coupling reaction resulting in A-ring modification. The design featured the chemoenzymatic transesterification of carbonates followed by the transformation of amino compounds to produce 1alpha,25-(OH)2-D3 A-ring C-5 carbamates. Varying chemical reactivities were determined by the type of solvents used.

A study of the steric requirements inside the vitamin D sterol-binding pocket of vitamin D-binding protein (DBP) has been conducted. The analysis was performed by considering the conformational structures of a number of bromoacetate derivatives of 25-hydroxyvitamin D3 and 1alpha,25-dihydroxyvitamin D3. The results indicate that the vitamin D sterol-binding pocket in DBP is sterically restrictive, a feature that has potential application in the design of future vitamin D-based drugs.

The oxidation of vitamin D2 (ergocalciferol) or its 3beta-acetyl derivative by methyl(trifluoromethyl)dioxirane and dimethyldioxirane, respectively, was investigated. The reaction of vitamin D2 afforded a single tetraepoxide diastereoisomer in high yield. In contrast, its 3-acetyl derivative produced 5,6(beta);7,8(beta);10,19(alpha)-triepoxide as the principal product and a tetraepoxide which was later converted to its C25-hydroxy derivative.

The study of the enzymatic acylation of the vitamin D A-ring enzymes 2a, 2b, and 3a reveals that Chromobacterium viscosum lipase is the most suitable enzyme for effecting practical levels of regioselectivity. Only the cis diol 2b is acylated at the allylic C-3 hydroxyl, while other stereoisomers are acylated at C-5. Direct application of this technique results in convenient kinetic resolution of fragment (plus or minus)-4.

The stereoselective conversion of a hydrindenone to (plus or minus)-bromohydrindenone constitutes the main step in a four-step synthesis of a racemic CD-intermediate from racemic hydrindenone. An epoxide, obtained from the stereoisomer, undergoes reductive ring opening regioselectively and enables transposition of oxygen from C-9 to C-8, which results in a (plus or minus)-hydrindanol. In the final step, the racemic hydrindanol is obtained through Horner-Wittig reaction and hydrogenation.

Hypersensitive bands of the vitamin D responsive element and the OC box domain transcription intensity consequent to upregulation of osteocalcin suggest chromatin involvement in osteocalcin gene response to physiological modulation. Nonosseous cells lacking osteocalcin gene expression do not exhibit hypersensitivity despite their response to a histone gene promoter. The presence of a nucleosome between two DNase I hypersensitive sites indicates a suitable conformation for binding factors.

Active vitamin D analogs were synthesized. A highly diastereoselective process was used with conjugation of Me2CuLi to a steroid and enones as a key step. The resulting analogs had side chains with restricted conformational flexibility. Readily available 1alpha-hydroxylated C steroid was used to start the synthesis. Results indicated that addition of Me2CuLi was a thermodynamically controlled process. Only the (22S)-isomer showed ability to bind with active vitamin D3.

An improved synthetic route to 1alpha,25-dihydroxyvitamin D2 involves the nucleophilic attack of stannylacetylene on a pregnyl dioxanone, obtained from a dinorcholanol and (3R)-3-hydroxybutyric acid. The attack cleaves the ketone's dioxo-ring and installs the acetylene. Conversion of the resulting alcohol into a ketone and construction of the triene by cross-coupling with a cyclohexenylinyne leads to the target 1alpha,25-dihydroxyvitamin D2.

A study is made on new approaches for the synthesis of vitamin D metabolites using palladium-catalyzed reactions. Previous studies have shown the applicability of Pd-catalyzed alkylative cyclization for 1,6-enynes. This study, however, indicates additional applicability to 1,7-enynes. The new concept for vitamin D synthesis is based on an A ring formation which accompanies its attachment to a specific CD fragment. The new and extremely chemoselective Pd-catalyzed reactions can be useful in the synthesis of analogues.

A new mechanistic scenario that complements and unifies the large amount of experimental data on the synthesis of vitamin D using the photochemical electrocyclic ring opening of the 1,3-diene unit in ergosterol is presented. The photochemical reaction network and the photoequilibrium involved in this process was studied using MM-VB, a new computational technique combining the molecular mechanics method and the Heitler-London valence bond theory. The ab initio calculations are verified on the 1,3,5-hexatriene model system using theMC-SCF porgram. The results show the existence of three structural bottlenecks through which the excited state passes in order to return to the ground state.

The diastereoselective synthesis of the cis-fused isomer of a 25-hydroxy Grundmann ketone was undertaken using the Diels-Alder reaction on a homochiral ester. This method used the chirality at C24 of the side chain to achieve stereochemical control over the fused ring system. The ester enolate Claisen rearrangement of the dimethylacryloyl ester derived from the benzyl-protected erythro isomer resulted in the C17 and C20 stereochemistry of vitamin D.

Trans-hydrindanol and trans-hydrindanone served as precursors in the synthesis of the CD and side-chain fragments of vitamin D metabolites and analogues. An enedione and a tosylate compound provided the starting materials for the corresponding syntheses of the hydrindanol and the hydrindanone. The key procedure in the hydrindanol synthesis involved Wilkinson catalyst-mediated hydrogenation of the hydrindenol intermediates which led to the formation of the desired trans-product in 65% yield. Both hydrindanol and hydrindanone compounds produced the diol form of the CD fragment in 81% and 80% yields, respectively.

Results reveal that the silylcopper catalyst, dimethylphenylsilylcopper(I), efficiently brings about reductive bromination of Hajos dione. Data indicate that the overall production of the CD synthon from Hajos dione jumps from 22% to 47%.

Results demonstrate that the silylcopper catalyst, dimethylphenylsilylcopper(I), efficiently participates in the reductive bromination of Hajos dione. Data suggest that the method is reproducible, amenable to scale-up, and high yielding. The yield of the CD synthon from Hajos dione is about 47%.

A study was conducted to analyze the residues critical for the structure, stability, oligomerization and binding to 1,25-dihydroxyvitamin [D.sub.3] (vit D) as well as two small molecules that is all-trans-retinol (ATR) and curcumin (CCM). Findings highlight the insight into COMPcc and its role but also useful guidelines for the design of stable, pentameric coiled-coils capable of selectively storing and delivering various small molecules.

A convenient five-step route is described for 25-hydroxylated vitamin [D.sub.3] compounds on (hydroxymethyl)polystyrene support. The title compounds are released from the resin by nucleophilic attack on the ester carbonyl group using organometallic reagents, thus providing an opportunity for the efficient generation of 26,27-labeled compounds and also for diversification at the side chain without need for a pool of side chain fragments.

A convergent strategy in the preparation of 1alpha-hydroxyvitamin D analogues involving the creation of ring A from an acyclic unit was reported. The enyne unit was synthesized from the monoacetal of malonaldehyde. The enantiomeric excess and absolute configuration of the alcohols were determined from NMR analysis of O-methylmandelate ester. Bromoolefination of Grundmann's ketone gave a high E selectivity which was attributed from dipole-dipole effects. A Pd-catalyzed alkylative cyclization followed to give the silylated vitamin.

Two efficient synthetic approaches to 1alpha,25-dihydroxy-16-ene-vitamin D3 and its analogues at C-20 have been developed. Among the key features of both routes are the stereo- and regiocontrolled cuprate S(sub N)2' syn addition to allylic carbamates. In route A, the cuprate chemistry is carried out prior to the introduction of the vitamin D triene unit while in route B, the cuprate chemistry is carried out on intermediates that already have the vitamin D triene unit and the allylic carbamate system.