Synthesis of thromboxane A2 analog DL-(9,11), (11,12)-dideoxa-(9,11)-epithio-(11,12)-methylene-thromboxane A2

A synthesis of the thromboxane A₂ analog, $\text{dl}$-(9,11), (11,12)-dideoxa-(9,11)-epithio-(11,12)-methylene-thromboxane A₂ is described.     

Synthesis of thromboxane A2 analog DL-(9,11), (11,12)-dideoxa-(9,11)-methylene-(11,12)-epithio-thromboxane A2 methyl ester

A synthesis of the thromboxane A₂ analog, $\text{dl}$-(9,11) ,(11,12)-dideoxa-(9,11)-methylene-(11,12)-epithio-thromboxane A₂ methyl ester $\text{2}$, is described.     

Synthesis of thromboxane A2 analog,dl-(9,11)-methano-(11,12)-amino thromboxane A2

A synthesis of nitrogen containing thromboxane, A₂ analog, $\text{dl}$-(9,11)-methano-(11,12)-amino thromboxane A₂ ($\text{1}$) is described.     

A convenient route to (+)-(9,11)-epithia-(11,12)-methano-thromboxane A2, from prostaglandin E2, methyl ester

(+)-(9,11)-Epithia-(11,12)-methano-thromboxane A₂ which is of great importance in thromboxane research, has been synthesized from prostaglandin E₂ methyl ester.     

Synthesis of a stable analogue of thromboxane A1 (±)-9a-homo-(11,12)-deoxa-(11,12)-methylene thromboxane A1

The thromboxane A₁ (TXA₁) analogue (1) has been synthesised from the ketone (2).     

Synthesis of a stable analog of thromboxane A2 with methylene replacing the 9,11-bridging oxygen

A total synthesis of the thromboxane A₂ analog ($\text{2}$) is described.     

Synthesis of structure analogues of thromboxane A2

Analogues I of thromboxane A₂ (TXA₂) in which the ether linkages are replaced by carbon groupings have been synthesised by elaboration of a commercially available pinene derivative IIb.     

Synthesis of thromboxane A2 analogs—2 : (±)-Thiathromboxane A2

The total synthesis of (±)-11a-methano- 9,11-thiathromboxane A₂(1), the sulfur analog of thromboxane A₂ is described     

A simple approach to carbocyclic thromboxane A2 from a cyclubutane

A short route from the cyclobutane derivative (1) to the key intermediate (4) allows easy access to the carbocyclic thromboxane A₂ analogue (5).     

Synthesis of 9α,11α-thiathromboxane A2 methyl ester

The synthesis of thromboxane A₂ (TXA) analogue, 9α,11α-thia-TXA₂ methyl ester $\text{2}$, in which the oxygen atom in the oxetane ring of TXA₂ was replaced by a sulfur atom, is described.     

Synthesis of thromboxane A2 analogs—3 : (+)-Thiathromboxane A2

(+)-11a-methano-9,11-thiathiromboxane A₂(1) was synthesized from prostaglandin A₂ and prostaglandin E₂.     

Stereoselective syntheses of the glycosidase inhibitors hyacinthacine A2, hyacinthacine A3 and 5-epi-hyacinthacine A3

Stereoselective syntheses of the naturally occurring glycosidase inhibitors hyacinthacines A₂ and A₃ are reported. In the case of hyacinthacine A₂, the pyrrolizidine system was created from an acyclic precursor via a double cyclization procedure with a one-pot formation of two C-N bonds. In the case of hyacinthacine A₃, the two C-N bonds were created in separate steps. In addition, the non-natural epimer at C-5 of hyacinthacine A₃ was obtained.     

A direct stereospecific synthesis of 9,11-etheno- and 9,11-ethano-PGH1 derivatives

The reaction of methyl 10-oxodec-S-ynoate with cyclopentadiene is reported as the key step in the synthesis of 9,11-etheno- and 9,11-ethano-PGH₁ derivatives.     

Synthesis of thromboxane A2 analogs—1 : (±)-Dimethanothromboxane A2

The stable thromboxane A₂ analog (±)-dimethanothromboxane A₂ 1 was synthesized from bicyclo[3.1.1]heptane 2 via the tricyclic compound 4.     

A simple synthesis of a stable thromboxane A2 analogue

A simple synthetic route, which appears to have some general utility, has been used to obtain a Bicyclo[2.2.1]heptane analogue of Thromboxane A₂.     

Synthesis of (R)-3,4-dihydro-2H-pyran-2-carboxaldehyde: application to the synthesis of potent adenosine A2A and A3 receptor agonist

Synthesis of potent adenosine A_2A and A₃ receptor agonist from the modification of adenosine-5′-N-ethylcarboxamide (NECA) has been reported. Diastereoisomer possessing an (R)-3,4-dihydro-2H-pyranyl (DHP) moiety exhibited the highest affinity at the A_2A and A₃ receptors. The key steps involve the synthesis of (R)-3,4-dihydro-2H-pyran-2-carboxaldehyde (7), which was obtained through the enzyme-catalyzed kinetic resolution of (±)-2-acetoxymethyl-3,4-dihydro-2H-pyran (5).     

Une nouvelle famille structurale: Les titanoniobates et titanotantalates A2Nb6TiO18 et A2Ta6TiO18

New ternary oxides A₂M₆TiO₁₈ (A = Rb, Cs; M = Ta, Nb) have been synthesized by reaction between M₂O₅ and TiO₂ oxides and A₂CO₃ carbonates. They crystallize in the hexagonal system in a cell of dimensions a and c near 7.5 and 8.2 Å, respectively. There is one formula unit in the cell, in good agreement with the observed densities 4.38 and 4.78 for A₂Nb₆TiO₁₈, 6.62 and 6.93 for A₂Ta₆TiO₁₈. The structure has been determined from powder diffraction patterns, from the 64 first reflections (i.e., 190 hkl), and refined to R₁ values ranging from 0.06 and 0.08. It can be described from a basic unit of composition (M₆O₂₄) formed of 3 × 2 octahedra of oxygen atoms, sharing edges and corners, with MO distances ranging from 1.8 and 2.2 Å. Relations with the hexagonal tungsten bronze and pyrochlore-type structures are discussed.     

Synthesis of gibberellins A8 and A56 from gibberellin A3

A mixture of gibberellin A₃ derivatives with 1(10)-ene-2,3-diol and 1(10)-ene-2,3-diol (2:5) groups, readily obtained from gibberellin A₃, has been used for a new and simple synthesis of gibberellin A₈ and its esters. The hydrolysis of GA₃ and the iodolactonization of a mixture of the 2-epimers was carried out in aqueous solution in a single flask, as also was a synthesis of GA₅₆ from GA₃ by a method that we have modified. The mixture of 1-iodides of GA₈ and GA₅₆ was separated by chromatography on SiO₂ in the form of methyl or p-bromophenacyl esters which were then deiodinated and the methyl or p-bromphenacyl ester of GA₈ was isolated. Free GA₈ was obtained by the dephenylation of the latter ester. By two-dimensional NMR spectroscopy we succeeded in assigning all the signals in the¹³C and¹H NMR spectra of the methyl esters of GA₈ and GA₅₆. In an attempt to obtain GA₅ methyl ester by the action of trimethylchlorosilane/sodium iodide on the 2,3-diol system in GA₅₆ methyl ester, the 8,13-epimer of the latter was formed, the structure of its molecule being established from the results of X-ray structural analysis.Novosibirsk Institute of Organic Chemistry, Siberian Division of the Russian Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 663–669, September–October, 1994.     

Oxyallyls in synthesis: Preparation of tricyclic thromboxane A2 analogues

We describe the formation of 1-(dimethoxymethyl)-2-(2-phenylethenyl)-8-oxabicyclo[3.2.1]oct-6-en-3-ol (4) using oxyallyl methodology, and conversion of this into two 2,6-dioxatricyclo[3.3.1.0^3,7] nonanes (9) and (10) via iodoetherification and reduction. These compounds were then elaborated into the novel thromboxane analogues (11) and (12).     

On the structure of thromboxane A2

The reactions of the 2-alkoxyoxetane 5 with sodium azide and methanol yield the α-azidoether 7 and the dimethyl acetal 8, respectively, paralleling reactions reported for TXA₂. The hydrolysis of 5 reported by Bruice to involve general acid catalysis proceeds at a rate similar to that reported for TXA₂. All these cleavage reactions are most likely to proceed by the same mechanism. These findings support structure 1 for TXA₂.