Copper-catalyzed asymmetric conjugate addition of organometallic reagents to extended Michael acceptors

• Thibault E. Schmid,
• Sammy Drissi-Amraoui,
• Christophe Crévisy,
• Olivier Baslé and
• Marc Mauduit

Beilstein J. Org. Chem. 2015, 11, 2418–2434, doi:10.3762/bjoc.11.263

• were employed in total synthesis strategies (Figure 3). Wieland and Anner took advantage of the reaction selectivity in the synthesis of steroids as early as 1967 [14]. For instance, the product (rac)-13 was obtained in 43% yield by reacting a methylmagnesium bromide with the steroid derivative 12 in

Dicarboxylic esters: Useful tools for the biocatalyzed synthesis of hybrid compounds and polymers

• Ivan Bassanini,
• Karl Hult and
• Sergio Riva

Beilstein J. Org. Chem. 2015, 11, 1583–1595, doi:10.3762/bjoc.11.174

• 18, obtained by linking together a steroid (cortisone, 14) and an alkaloid (colchicoside, 15; thiocolchicoside, 16). Worth of notice the use, among others, of activated esters of dithio-dicarboxylic acids, in 18. More recently Kren and coworkers have synthesized hybrid dimeric antioxidants 23–25

N-Alkyl derivatives of diosgenyl 2-amino-2-deoxy-β-D-glucopyranoside; synthesis and antimicrobial activity

• Agata Walczewska,
• Daria Grzywacz,
• Dorota Bednarczyk,
• Małgorzata Dawgul,
• Andrzej Nowacki,
• Wojciech Kamysz,
• Beata Liberek and
• Henryk Myszka

Beilstein J. Org. Chem. 2015, 11, 869–874, doi:10.3762/bjoc.11.97

• . Keywords: antimicrobial activities; D-glucosamine; diosgenin glycosylation; N-alkylation; Introduction Saponins are a group of steroid or triterpenoid glycosides, widely distributed in the plant kingdom [1]. Saponins are characteristic by their foaming properties in aqueous solution, causing them to be

Electrochemical oxidation of cholesterol

• Jacek W. Morzycki and
• Andrzej Sobkowiak

Beilstein J. Org. Chem. 2015, 11, 392–402, doi:10.3762/bjoc.11.45

• affords different products depending on the reaction conditions. Keywords: allylic oxidation; cholesterol; electrochemical halogenation; electrochemical oxidation; Introduction Cholesterol is the most common steroid in the mammalian body. It is necessary to ensure a proper membrane permeability and

• fluidity. It also serves as a precursor for the biosynthesis of steroid hormones, bile acids, and vitamin D [1]. The chemical oxidation of cholesterol is a crucial reaction in the synthesis of many compounds that are of pharmaceutical importance [2][3]. At the close of the previous century, special

• reaction carried out with 1,2:3,4-di-O-diisopropylidene-α-D-galactopyranose yielded glycoconjugate 23 with an ether bond between the sugar and steroid molecules. In further studies on the preparation of glycoconjugates from 3β-hydroxy-Δ5-steroids, various derivatives were applied, such as thioethers [44

3α,5α-Cyclocholestan-6β-yl ethers as donors of the cholesterol moiety for the electrochemical synthesis of cholesterol glycoconjugates

• Aneta M. Tomkiel,
• Adam Biedrzycki,
• Jolanta Płoszyńska,
• Dorota Naróg,
• Andrzej Sobkowiak and
• Jacek W. Morzycki

Beilstein J. Org. Chem. 2015, 11, 162–168, doi:10.3762/bjoc.11.16

• cyclosteroid (i-steroid) rearrangement is a well-known steroid reaction [6]. The solvolysis of cholesteryl p-tosylate proceeds via the SN1 mechanism with the formation of a mesomerically stabilized carbocation. The addition of a nucleophile (alcohol, water, etc.) may occur either to C-3 or C-6, depending on

• -steroid ethers are frequently prepared for simultaneous protection of both 3β-ol and Δ5 groups in sterols. The cycloreversion that occurs under acidic conditions allows to recover sterol functions. We thought that such highly energetic i-steroid ethers would easily generate the mesomeric carbocation

• electrolyte. The steroid (0.30 mmol) and sugar (0.36 mmol) substrates were introduced into the anodic compartment together with 0.3 g of 3 Å molecular sieves added to eliminate traces of water, whereas anionite (1.5–2 g, Dowex 2 × 8, 200–400 mesh, perchlorate form) was placed in the cathodic compartment to

A study on the inhibitory mechanism for cholesterol absorption by α-cyclodextrin administration

• Takahiro Furune,
• Naoko Ikuta,
• Yoshiyuki Ishida,
• Hinako Okamoto,
• Daisuke Nakata,
• Keiji Terao and
• Norihiro Sakamoto

Beilstein J. Org. Chem. 2014, 10, 2827–2835, doi:10.3762/bjoc.10.300

• inclusion property with lipophilic molecules [1]. For example, α-CD has a high affinity for fatty acids, flavor molecules and other hydrophobic molecules [2][3][4]. However, α-CD has a low affinity for the steroid structure because the cavity size of α-CD is smaller than the structure [3][5]. α-CD has

Total synthesis of the proposed structure of astakolactin

• Takayuki Tonoi,
• Keisuke Mameda,
• Moe Fujishiro,
• Yutaka Yoshinaga and
• Isamu Shiina

Beilstein J. Org. Chem. 2014, 10, 2421–2427, doi:10.3762/bjoc.10.252

• sesterterpenoid bearing a furan unit and an eight-membered lactone tethered by a non-conjugated triene chain (Figure 1). Although the proposed structure of compound 1 is unusual, given that a number of compounds isolated from sponges of the same species have a steroid-like structure [7][8][9], the structure does

Application of cyclic phosphonamide reagents in the total synthesis of natural products and biologically active molecules

• Thilo Focken and
• Stephen Hanessian

Beilstein J. Org. Chem. 2014, 10, 1848–1877, doi:10.3762/bjoc.10.195

Synthesis of isoprenoid bisphosphonate ethers through C–P bond formations: Potential inhibitors of geranylgeranyl diphosphate synthase

• Xiang Zhou,
• Jacqueline E. Reilly,
• Kathleen A. Loerch,
• Raymond J. Hohl and
• David F. Wiemer

Beilstein J. Org. Chem. 2014, 10, 1645–1650, doi:10.3762/bjoc.10.171

• CoA reductase (HMGCoA) is viewed as the first committed step of isoprenoid and steroid biosynthesis, and is the target of the statin class of cholesterol-lowering agents including lovastatin (1, Figure 1) and pravastatin (2) [1]. The downstream enzyme farnesyl diphosphate synthase (FDPS) is the target

C–H-Functionalization logic guides the synthesis of a carbacyclopamine analog

• Sebastian Rabe,
• Johann Moschner,
• Marina Bantzi,
• Philipp Heretsch and
• Athanassios Giannis

Beilstein J. Org. Chem. 2014, 10, 1564–1569, doi:10.3762/bjoc.10.161

• was thought to establish the C-nor-D-homo steroid system, and a gold-catalyzed amination/annulation/aromatization sequence was planned to install the pyridine F-ring. Diazo compound 3 originates from diene 4 through standard transformations, the latter being accessible from commercially available and

• intermediate (not shown, triethylsilyl trifluoromethanesulfonate, 2,6-lutidine, CH2Cl2, 0 °C; then HF·pyridine, THF, 0 °C, 67% yield for the two steps) [28] gave hydroxy ketone 7. The remaining homoallylic alcohol was then masked as an i-steroid [29][30] (para-toluenesulfonyl chloride, cat. 4

• this point, extensive experimentation suggested a change of protecting groups to enable the pending C–H insertion reaction at C17. Therefore, the i-steroid was reverted to the homoallylic alcohol (cat. para-toluenesulfonic acid, 1,4-dioxane/H2O, 10:1, 65 °C), the methyl ester was hydrolyzed under basic

Substrate dependent reaction channels of the Wolff–Kishner reduction reaction: A theoretical study

• Shinichi Yamabe,
• Guixiang Zeng,
• Wei Guan and
• Shigeyoshi Sakaki

Beilstein J. Org. Chem. 2014, 10, 259–270, doi:10.3762/bjoc.10.21

• convenient method of the W-K reduction [4][5]. The method involves heating R1(R2)C=O, KOH and hydrazine hydrate (H2N–NH2·H2O) together in diethylene glycol (DEG in Scheme 1). This method gives the products from steroid ketones in a one-pot reaction and with a high yield. Scheme 2 shows the reaction mechanism

Cyclopamine analogs bearing exocyclic methylenes are highly potent and acid-stable inhibitors of hedgehog signaling

• Johann Moschner,
• Anna Chentsova,
• Nicole Eilert,
• Irene Rovardi,
• Philipp Heretsch and
• Athanassios Giannis

Beilstein J. Org. Chem. 2013, 9, 2328–2335, doi:10.3762/bjoc.9.267

• , 0 °C, 93%), (2) hydroboration/oxidation (9-BBN, THF, 70 °C; then NaBO3, H2O, 50 °C, 91%) and finally, (3) oxidative cyclization (BAIB, cat. TEMPO, CH2Cl2, 25 °C, 73%) was employed. Deprotection of the silyl ether (HF, MeCN, 25 °C, 87%) and base-induced rearrangement of the steroid skeleton via the

Self-assembly of 2,3-dihydroxycholestane steroids into supramolecular organogels as a soft template for the in-situ generation of silicate nanomaterials

• Valeria C. Edelsztein,
• Andrea S. Mac Cormack,
• Matías Ciarlantini and
• Pablo H. Di Chenna

Beilstein J. Org. Chem. 2013, 9, 1826–1836, doi:10.3762/bjoc.9.213

• key to the directed design of new organogels. We report herein the organogelating property of four stereoisomers of the simple steroid 2,3-dihydroxycholestane. Only the isomer with the trans-diaxial hydroxy groups had the ability to gelate a broad variety of liquids and, thus, to be a super

• possess a complementary donor–acceptor hydrogen bond motif, such as for instance amides, ureas, carbamates, saccharides, ammonium carboxylate salts, etc. A rod-like molecular shape is also a general structural requirement for steroid derived LMOGs because it allows a good face to face molecular contact to

• versatile units on which to base the systematic design of functional LMOGs for the gelation of organic solvents. Neither cholesterol nor cholestanol are gelator molecules, and although a variety of steroid derivatives has been analyzed over the years only a few simple analogues are known to be

Recent progress in the discovery of small molecules for the treatment of amyotrophic lateral sclerosis (ALS)

• Allison S. Limpert,
• Margrith E. Mattmann and
• Nicholas D. P. Cosford

Beilstein J. Org. Chem. 2013, 9, 717–732, doi:10.3762/bjoc.9.82

• reduced astrocyte reactivity and motor neuron death, as well as prolonged the lifespan of the treated animals by two weeks. Steroid treatment: Dihydrotestosterone (DHT, 36) treatment increases muscle mass and has been demonstrated to be neuroprotective [77]. Chronic diseases, such as ALS, which display

Some aspects of radical chemistry in the assembly of complex molecular architectures

• Béatrice Quiclet-Sire and
• Samir Z. Zard

Beilstein J. Org. Chem. 2013, 9, 557–576, doi:10.3762/bjoc.9.61

• potent steroid contraceptive desogestrel (79), as outlined in Scheme 16 [36]. Thus, radical addition to alkene 76 furnishes intermediate 77, after deprotection of the second ketone group. Exposure of the latter compound to base results in the formation of bicycle 78 as one diastereomer. While the

• the 11-position (steroid numbering) and therefore allows the ready subsequent introduction of various substituents on this important position. In this quite general route to cyclohexenes, the requisite 2-allyl ketones are readily available by alkylation but also, and more importantly, by the

• alkenes, as indicated by the two examples in Scheme 28. The first represents a one-step synthesis of a steroid C-glycoside 149 [66], while the second illustrates a modular approach where the formation of alkene 152 is associated with the initial addition–transfer of cortisone derived xanthate 150 to vinyl

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

Highly enantioselective access to cannabinoid-type tricyles by organocatalytic Diels–Alder reactions

• Stefan Bräse,
• Nicole Volz,
• Franziska Gläser and
• Martin Nieger

Beilstein J. Org. Chem. 2012, 8, 1385–1392, doi:10.3762/bjoc.8.160

• used method [3][4][5][6][7]. Some examples are shown in Figure 1. The first application was the total synthesis of the steroid Cortisone (1) in 1952 by Woodward et al. [8]. Another example, indicating the importance of the well-known [4 + 2] cycloaddition in natural-product synthesis, is the first

Coupled chemo(enzymatic) reactions in continuous flow

• Ruslan Yuryev,
• Simon Strompen and
• Andreas Liese

Beilstein J. Org. Chem. 2011, 7, 1449–1467, doi:10.3762/bjoc.7.169

• steroid 76, and the overall product recovery was increased by a factor of about 4.3. A space-time yield of approximately 2.2 mg L−1 day−1 was achieved after three days of operation. Conclusion The examples of continuous coupled (chemo)enzymatic reactions reviewed herein demonstrate that such

Pd/C-mediated synthesis of α-pyrone fused with a five-membered nitrogen heteroaryl ring: A new route to pyrano[4,3-c]pyrazol-4(1H)-ones

• Dhilli Rao Gorja,
• Venkateswara Rao Batchu,
• Ashok Ettam and
• Manojit Pal

Beilstein J. Org. Chem. 2009, 5, No. 64, doi:10.3762/bjoc.5.64

• shown anticancer properties in vitro [7]. Recently, incorporation of another five-membered ring, e.g. pyrazole pyrone moieties in a single molecule (A, Figure 1) has been reported to provide polycyclic azaheteroaromatics with a steroid-like skeleton [8]. This initiative was based on the assumption that