Alternaric acid: formal synthesis and related studies

• Michael C. Slade and
• Jeffrey S. Johnson

Beilstein J. Org. Chem. 2013, 9, 166–172, doi:10.3762/bjoc.9.19

• acetonide formation provided 7, and ozonolysis afforded Ichihara’s aldehyde 8 (Scheme 3). Interception of this intermediate thus constituted a formal synthesis; the precedent for the C8–C9 olefination involved a classical, three-step Julia olefination sequence [24]. To demonstrate proof-of-concept for a

Influence of cyclodextrin on the solubility of a classically prepared 2-vinylcyclopropane macromonomer in aqueous solution

• Helmut Ritter,
• Jia Cheng and
• Monir Tabatabai

Beilstein J. Org. Chem. 2012, 8, 1528–1535, doi:10.3762/bjoc.8.173

• with a Viscotek GPCmax VE2001 using DMF as the eluent at 60 °C (flow rate: 1 mL/min). The ozonolysis was carried out on an ozone generator by Fischer Technology. In this ozone generator 45–50 liters of oxygen per hour was provided. Synthesis of amino-terminated poly(N-isopropylacrylamide) 3 A) In water

• was calculated; in this case ca. 500 mg, corresponding [Me2-β-CD]/[5] ratio of about 0.02:1. Ozonolysis of copolymer 8 A condensation trap with 1 g of copolymer 8 is filled up with methanol until the inlet is immersed in the solution. The cold trap is connected with the ozone generator and flushed

• with nitrogen for 10 min. Then, the solution is cooled to −74 °C and finally flushed with oxygen. After starting the ozone generator the oxygen is converted to ozone. The ozonolysis continues until the solution turns blue due to the excess of ozone. After shutting off the ozone generator, the solution

Stereoselective synthesis of trans-fused iridoid lactones and their identification in the parasitoid wasp Alloxysta victrix, Part I: Dihydronepetalactones

• Nicole Zimmermann,
• Robert Hilgraf,
• Lutz Lehmann,
• Daniel Ibarra and
• Wittko Francke

Beilstein J. Org. Chem. 2012, 8, 1246–1255, doi:10.3762/bjoc.8.140

• the key intermediate 16 – which shows two differentiated primary alcohol functions – started from enantiomerically pure (R)-limonene (14, Scheme 2). Ozonolysis followed by reductive workup with dimethyl sulfide produced (3R)-3-(1-methylethenyl-6-oxoheptanal), which yielded the formyl cyclopentene 15

2-Allylphenyl glycosides as complementary building blocks for oligosaccharide and glycoconjugate synthesis

• Hemali D. Premathilake and
• Alexei V. Demchenko

Beilstein J. Org. Chem. 2012, 8, 597–605, doi:10.3762/bjoc.8.66

• can be reverted as needed (active–latent strategy). Direct conjugation of the AP moiety to biomolecules, monolayers, arrays, etc., should be possible by executing thiol–ene chemistry [43], ozonolysis/reductive amination [44][45][46], or other ligation protocols [47][48]. Experimental General remarks

Homoallylic amines by reductive inter- and intramolecular coupling of allenes and nitriles

• Peter Wipf and
• Marija D. Manojlovic

Beilstein J. Org. Chem. 2011, 7, 824–830, doi:10.3762/bjoc.7.94

• methodology, we demonstrated that the homoallylic amine products could be readily converted to synthetically useful building blocks, such as β-amino acids (Scheme 4). N-Boc-protection of the primary amine 12 followed by ozonolysis under Marshall’s conditions [40] yielded the β-amino acid derivative 24. The

When cyclopropenes meet gold catalysts

• Frédéric Miege,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2011, 7, 717–734, doi:10.3762/bjoc.7.82

• considering a twist-boat transition state model in which the gold center and the allylic benzyloxymethyl substituents both occupy axial positions in order to avoid 1,3-allylic strain with the vinylic methyl groups. The isopropylidene group in compound 60 can be cleaved by ozonolysis to give the corresponding

The arene–alkene photocycloaddition

• Ursula Streit and
• Christian G. Bochet

Beilstein J. Org. Chem. 2011, 7, 525–542, doi:10.3762/bjoc.7.61

• to the desired compound via a thermal vinylcyclopropane–cyclopentene rearrangement. All obtained photocycloaddition compounds can be converted into the target by this means. The cyclopropane ring was opened by a Birch-type reduction. Oxidation of the primary alcohol and ozonolysis of the double bond

Molecular rearrangements of superelectrophiles

• Douglas A. Klumpp

Beilstein J. Org. Chem. 2011, 7, 346–363, doi:10.3762/bjoc.7.45

• ). Isomerization of 2-decalone (51). Rearrangement of the acyl-dication 58. Reaction of dialkylketone 64. Ozonolysis in superacid. Rearrangement of 1-hydroxy-2-methylcyclohexane carboxylic acid (79) in superacid. Isomerization of the 1,5-manxyl dication 87. Energetics of isomerization. Rearrangement of dication 90

Dipyridodiazepinone derivatives; synthesis and anti HIV-1 activity

• Nisachon Khunnawutmanotham,
• Nitirat Chimnoi,
• Arunee Thitithanyanont,
• Patchreenart Saparpakorn,
• Kiattawee Choowongkomon,
• Pornpan Pungpo,
• Supa Hannongbua and
• Supanna Techasakul

Beilstein J. Org. Chem. 2009, 5, No. 36, doi:10.3762/bjoc.5.36

• bromo compounds 18. The diazepinone ring was formed by treatment with sodium hexamethyldisilazane in pyridine to yield tricyclic compounds 19. Coupling of 19 with vinyltributyltin in the presence of tetrakis(triphenylphosphine) palladium(0) provided 8-vinyl compounds 20 which underwent ozonolysis to

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33

• exocyclic olefin was then converted to the corresponding ketone through ozonolysis. The ozonide and N-oxide were reduced with dimethyl sulfide at the end of the reaction. Using the Gardner protocol [96] to hydroxylate the alpha position of the resultant ketone failed to give any α-ketol, but instead

An expedient synthesis of 5-n-alkylresorcinols and novel 5-n-alkylresorcinol haptens

• Kirsti Parikka and
• Kristiina Wähälä

Beilstein J. Org. Chem. 2009, 5, No. 22, doi:10.3762/bjoc.5.22

• -dimethoxybenzaldehyde (18–48% yields whenever reported) [22][23][24][25][26]. Additional synthetic methods have been developed for shorter chain AR (ozonolysis product of a pentadecylresorcinol (C15

Recent progress on the total synthesis of acetogenins from Annonaceae

• Nianguang Li,
• Zhihao Shi,
• Yuping Tang,
• Jianwei Chen and
• Xiang Li

Beilstein J. Org. Chem. 2008, 4, No. 48, doi:10.3762/bjoc.4.48

• THF unit 140 was then constructed by ozonolysis of the alkenol 137 to give the lactol 138. Treatment of 138 with an excess of propargyl alcohol afforded 139, which was followed by anomeric O-C rearrangement to give 140. The hetero-Diels-Alder (HDA) reaction between diene 141 and nitrosobenzene

Synthesis of chiral cyclohexanes and carbasugars by 6-exo-dig radical cyclisation reactions

• Rajeev K. Shrivastava,
• Elise Maudru,
• Gurdial Singh,
• Richard H. Wightman and
• Keith M. Morgan

Beilstein J. Org. Chem. 2008, 4, No. 43, doi:10.3762/bjoc.4.43

• the “methyl” analogues 28 and 29 and these gave a similar outcome, (Scheme 6 and Scheme 5). Ozonolysis of the pair of geometric isomers 30 and 31 afforded the protected ketone 38 in 77% yield. The diastereomeric ketone 39 was obtained in 74% yield after similar treatment of 32 and 33. Removal of the

End game strategies towards the total synthesis of vibsanin E, 3-hydroxyvibsanin E, furanovibsanin A, and 3-O-methylfuranovibsanin A

• Brett D. Schwartz,
• Craig M. Williams and
• Paul V. Bernhardt

Beilstein J. Org. Chem. 2008, 4, No. 34, doi:10.3762/bjoc.4.34

• ) by a Claisen rearrangment (via the silyl enol ether) was not high yielding and produced many side products. Ozonolysis of 25 afforded the acetone sidechain (i.e. 26) in acceptable yield (50%). Other methods to unmask the ketone functionality failed, for example, dihydroxylation followed by oxidative

Total synthesis of the indolizidine alkaloid tashiromine

• Stephen P. Marsden and
• Alison D. McElhinney

Beilstein J. Org. Chem. 2008, 4, No. 8, doi:10.1186/1860-5397-4-8

• desired aldehyde to undergo retro-Mannich fragmentation, and so elected to carry out a reductive work-up to the ozonolysis procedure (Scheme 3). The desired alcohol 8 was obtained in a crude form and immediately subjected to reduction with lithium aluminium hydride to give our target tashiromine 1 in 36

Facile synthesis of two diastereomeric indolizidines corresponding to the postulated structure of alkaloid 5,9E- 259B from a Bufonid toad (Melanophryniscus)

• Angela Nelson,
• H. Martin Garraffo,
• Thomas F. Spande,
• John W. Daly and
• Paul J. Stevenson

Beilstein J. Org. Chem. 2008, 4, No. 6, doi:10.1186/1860-5397-4-6

• magnesium iodide gave the water soluble tertiary alcohol 1 in 96% yield. 7-Oxoheptanoic acid methyl ester was prepared by the literature procedure [36], by ozonolysis of 1-methoxycycloheptene, and then condensed with the amidoalcohol 1 with azeotropic removal of water to give the N,O-acetal 2 in 71% yield

Synthesis of the Benzo- fused Indolizidine Alkaloid Mimics

• Daniel L. Comins and
• Kazuhiro Higuchi

Beilstein J. Org. Chem. 2007, 3, No. 42, doi:10.1186/1860-5397-3-42

• 14 in 22% yield. The furan ring of 8a was converted to a carboxylic acid by ozonolysis to afford 15. The reductive amination of 8a with benzylamine provided 16α and 16β in good yield. The stereochemistry of these compounds was determined by NOESY NMR analysis. These functional groups, such as

A convenient allylsilane- N-acyliminium route toward indolizidine and quinolizidine alkaloids

• Roland Remuson

Beilstein J. Org. Chem. 2007, 3, No. 32, doi:10.1186/1860-5397-3-32

• diastereomers which were not separated. The hydroxylactam 34 was then cyclised to the quinolizidine isomers 35a and 35b on treatment with 4 equiv. of trifluoroacetic acid in a 7:3 ratio. Then, ozonolysis of 35a and 35b followed by reduction with dimethylsulfide furnished respectively 36a and 36b. Protection of

• two routes to the quinolizidine alkaloids lasubine I and lasubine II from methylenquinolizidinones 42a and 42b. They involved oxidation of the methylene group into a carbonyl which was then stereoselectively reduced to the hydroxyl group. The shortest route consisted of the ozonolysis of the methylene

• group followed by the simultaneous reduction of the two carbonyl groups of keto lactams 43a and 43b. Thus, treatment of 42a with ozone then with dimethyl sulfide afforded the expected keto lactam 43a in 91% yield. Ozonolysis of 42b led to keto lactam 43b in 63% yield. Reduction of 43a with lithium

The vicinal difluoro motif: The synthesis and conformation of erythro- and threo- diastereoisomers of 1,2-difluorodiphenylethanes, 2,3-difluorosuccinic acids and their derivatives

• David O'Hagan,
• Henry S. Rzepa,
• Martin Schüler and
• Alexandra M. Z. Slawin

Beilstein J. Org. Chem. 2006, 2, No. 19, doi:10.1186/1860-5397-2-19

• lead to poor conversions and a complex product mixture. As an alternative strategy ozonolysis in acetic acid, with a hydrogen peroxide work-up was explored [27][28], and this proved successful as illustrated in Scheme 8. For example, reaction of a 4:1 mixture of erythro- and threo- 13 led to the

• an extended chain conformation with both of the C-F bonds gauche to each other. One molecule of water is bound for every succinic acid molecule and this water clearly participates in hydrogen bonding to the carboxylic acid groups. The major by-product of the ozonolysis reaction of 13 was the vicinal

• . Hypothesis for the predominent retention of configuration during fluoride substitution via phenonium intermediate 18. Proposed C-C bond rotation during the preparation of 14 from cis-stilbene. Synthesis of erythro-19 via ozonolysis of erythro-13. Strategy for the preparation of diastereoisomers of erythro