Cobalt bis(acetylacetonate)–tert-butyl hydroperoxide–triethylsilane: a general reagent combination for the Markovnikov-selective hydrofunctionalization of alkenes by hydrogen atom transfer

• Xiaoshen Ma and
• Seth B. Herzon

Beilstein J. Org. Chem. 2018, 14, 2259–2265, doi:10.3762/bjoc.14.201

• the tertiary alcohol 4f in 69% yield (Table 1, entry 6). Inspired by Girijavallabhan and co-workers’ report [10], we were able to trap the tertiary alkyl radical with S-phenyl benzene thiosulfonate (PhSO2SPh, Table 1, entry 7) and Se-phenyl 4-methylbenzenesulfonoselenoate (TsSePh, Table 1, entry 8) [3

Heterogeneous acidic catalysts for the tetrahydropyranylation of alcohols and phenols in green ethereal solvents

• Ugo Azzena,
• Massimo Carraro,
• Gloria Modugno,
• Luisa Pisano and
• Luigi Urtis

Beilstein J. Org. Chem. 2018, 14, 1655–1659, doi:10.3762/bjoc.14.141

•  1). Finally, the tetrahydropyranylation of a tertiary alcohol 1j as well as of phenols 1k and 1l required, besides the employment of 2.0 equiv of DHP, relatively longer reaction times and higher temperatures. It is worth noting that under our mild reaction conditions we did not observe any

• , the mixture obtained by reacting 1f with 1.1 equiv of 2 and 3 mol ‰ of NH4HSO4@SiO2 in 2-MeTHF under dry Ar was filtered and dropwise added to a vigorously stirred freshly prepared solution of EtMgBr in the same solvent at rt. Aqueous work-up and flash chromatography afforded the desired tertiary

• alcohol 4fa in 78% yield (Scheme 4). Under similar conditions, protection of 1f in CPME, followed by filtration and dropwise addition of the resulting solution to a suspension of LiAlH4 in the same solvent, afforded the monoprotected diol 4fb in almost quantitative yield (Scheme 5). Conclusion The above

Investigations of alkynylbenziodoxole derivatives for radical alkynylations in photoredox catalysis

• Yue Pan,
• Kunfang Jia,
• Yali Chen and
• Yiyun Chen

Beilstein J. Org. Chem. 2018, 14, 1215–1221, doi:10.3762/bjoc.14.103

• (Scheme 4). Tertiary alcohols 6 were reported to be activated by cyclic iodine(III) reagents under photoredox conditions to generate alkoxyl radicals, and subsequently underwent β-fragmentation and alkynylation to yield 7 after eliminating the arylketone [25]. With tertiary alcohol 6a as the alkyl radical

• derivatives for radical alkynylations in photoredox catalysis. Reaction conditions: tertiary alcohol 6 (0.25 mmol, 2.5 equiv), alkynylbenziodoxole 3 (0.10 mmol, 1.0 equiv), Ru(bpy)3(PF6)2 (0.002 mmol, 0.02 equiv), and BI-OAc (0.25 mmol, 2.5 equiv) in 2.0 mL DCE for 24 h under a nitrogen atmosphere, unless

Copper-catalyzed asymmetric methylation of fluoroalkylated pyruvates with dimethylzinc

• Kohsuke Aikawa,
• Kohei Yabuuchi,
• Kota Torii and
• Koichi Mikami

Beilstein J. Org. Chem. 2018, 14, 576–582, doi:10.3762/bjoc.14.44

• have so far been reported [7][28][29][30]. In 2007, Gosselin and Britton et al. reported that treatment of ethyl trifluoropyruvate (1a) with (R)-BINOL-mediated organozincate as a chiral methylating regent provided the corresponding methylated tertiary alcohol 2a in moderate enantioselectivity (Scheme 1

From dipivaloylketene to tetraoxaadamantanes

• Gert Kollenz and
• Curt Wentrup

Beilstein J. Org. Chem. 2018, 14, 1–10, doi:10.3762/bjoc.14.1

• -type double bonds in the bisdioxines under acidic conditions generates a tertiary alcohol, which again undergoes a transannular oxa-Michael-type ring closure forming a tetraoxaadamantane. Free carboxylic acid functions are decarboxylated in this process (Scheme 7), but amide and ester functions are

Acid-catalyzed ring-opening reactions of a cyclopropanated 3-aza-2-oxabicyclo[2.2.1]hept-5-ene with alcohols

• Katrina Tait,
• Alysia Horvath,
• Nicolas Blanchard and
• William Tam

Beilstein J. Org. Chem. 2017, 13, 2888–2894, doi:10.3762/bjoc.13.281

• reactions. The scope of the reaction was successfully expanded to include primary, secondary, and tertiary alcohol nucleophiles. Through X-ray crystallography, the stereochemistry of the product was determined which confirmed an SN2-like mechanism to form the ring-opened product. Keywords: acid catalysis

• product (Table 3, entry 9). The cyclic alcohols cyclohexanol and cyclopentanol (Table 3, entries 10 and 11) produced low amounts of the ring-opened alcohol in a 24% and 26% yield, respectively. The use of a tertiary alcohol surprisingly resulted in a moderate yield, with tert-butanol producing a 50% yield

• of the reaction was successfully expanded to include primary, secondary, and tertiary alcohol nucleophiles. Through X-ray crystallography, the stereochemistry of the product was determined which confirmed an SN2-like mechanism to form the ring-opened product. Further investigation of the ring-opening

The photodecarboxylative addition of carboxylates to phthalimides as a key-step in the synthesis of biologically active 3-arylmethylene-2,3-dihydro-1H-isoindolin-1-ones

• Ommid Anamimoghadam,
• Saira Mumtaz,
• Anke Nietsch,
• Gaetano Saya,
• Cherie A. Motti,
• Jun Wang,
• Peter C. Junk,
• Ashfaq Mahmood Qureshi and
• Michael Oelgemöller

Beilstein J. Org. Chem. 2017, 13, 2833–2841, doi:10.3762/bjoc.13.275

• and subsequent column chromatography. All compounds 3 showed a characteristic pair of doublets between 3 and 4 ppm with a large geminal 2J coupling of 12–16 Hz for the benzylic methylene group (-CH2Ar) in their 1H NMR spectra and a singlet at 90 ± 3 ppm for the newly formed tertiary alcohol (C–OH) in

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• in the presence of an aryl or an alkyl group. The number of methylene units between the alkene and the tertiary alcohol function was studied: n = 0, 2, and 3 were suitable for generating thermodynamically favoured 3, 5, and 6-membered cyclic transition states; the reaction failed with n = 1, 4

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• nearly 90% yields for α-amino esters in 90–120 min (Scheme 18). The Ritter reaction is another significant carbon–nitrogen (C–N) bond forming reaction in the synthesis of amides [86]. Generally, a nitrile and a tertiary alcohol in presence of a strong acid react to create amides. Major drawbacks

Synthesis of alkynyl-substituted camphor derivatives and their use in the preparation of paclitaxel-related compounds

• M. Fernanda N. N. Carvalho,
• Rudolf Herrmann and
• Gabriele Wagner

Beilstein J. Org. Chem. 2017, 13, 1230–1238, doi:10.3762/bjoc.13.122

• coincide in 13 but are approximately 2 ppm apart in 12. Compounds 12 show a signal for the C=O near 206 ppm and one for the sulfonamide carbon at about 65 ppm. In compounds 13, there is a signal for the C=N around 194 ppm and one for the tertiary alcohol carbon near 73 ppm. All other signals of the camphor

Revaluation of biomass-derived furfuryl alcohol derivatives for the synthesis of carbocyclic nucleoside phosphonate analogues

• Bemba Sidi Mohamed,
• Christian Périgaud and
• Christophe Mathé

Beilstein J. Org. Chem. 2017, 13, 251–256, doi:10.3762/bjoc.13.28

• loss of AcOH leading to compound (+/−)-15 with 85% yield. The 1,3-allylic transposition of the hindered tertiary alcohol group under acidic conditions has not been reported yet for such compounds. It may conceivably that such a transposition occurs through the formation of an allylic carbocation which

Chromium(II)-catalyzed enantioselective arylation of ketones

• Gang Wang,
• Shutao Sun,
• Ying Mao,
• Zhiyu Xie and
• Lei Liu

Beilstein J. Org. Chem. 2016, 12, 2771–2775, doi:10.3762/bjoc.12.275

• -catalyzed enantioselective addition of aryl halides to both arylaliphatic and aliphatic ketones with high enantioselectivity in an intramolecular version, providing facile access to enantiopure tetrahydronaphthalen-1-ols and 2,3-dihydro-1H-inden-1-ols containing a tertiary alcohol. Keywords: arylation

• ; asymmetric catalysis; chromium; ketone; tertiary alcohol; Introduction Catalytic enantioselective carbon–carbon bond formation reactions have achieved enormous development during the last few decades as a consequence of the growing demand for enantiopure compounds in modern industry, especially the

• -catalyzed enantioselective arylation of ketones has never been reported to date [44]. Tetrahydronaphthalen-1-ol bears a chiral tertiary alcohol center and is a common structural motif in numerous biologically active natural products and clinical drugs [45]. The method to prepare these compounds through

Palladium-catalyzed ring-opening reactions of cyclopropanated 7-oxabenzonorbornadiene with alcohols

• Katrina Tait,
• Oday Alrifai,
• Rebecca Boutin,
• Jamie Haner and
• William Tam

Beilstein J. Org. Chem. 2016, 12, 2189–2196, doi:10.3762/bjoc.12.209

• cyclopropanated 7-oxabenzonorbornadiene derivatives using alcohol nucleophiles were investigated. The optimal conditions were found to be 10 mol % PdCl2(CH3CN)2 in methanol, offering yields up to 92%. The reaction was successful using primary, secondary and tertiary alcohol nucleophiles and was compatible with a

• 8a still recovered as an inseparable mixture (Table 5, entry 6). Unexpectedly, using a tertiary alcohol proceeded quicker than a secondary alcohol and resulted in complete conversion to ring-opened product 11p in a moderate yield of 56% (Table 5, entry 7). Cyclic alcohol nucleophiles were also

• regioisomer in all cases. The scope of the reaction was also successfully expanded to include various primary, secondary, and tertiary alcohol nucleophiles. Various chemical transformations of 7-oxabenzonorbornadiene 1. Nucleophilic ring-opening reactions of 7-oxabenzonorbornadiene 1. Preparation of

Practical synthetic strategies towards lipophilic 6-iodotetrahydroquinolines and -dihydroquinolines

• David R. Chisholm,
• Garr-Layy Zhou,
• Ehmke Pohl,
• Roy Valentine and
• Andrew Whiting

Beilstein J. Org. Chem. 2016, 12, 1851–1862, doi:10.3762/bjoc.12.174

• chromatography or distillation. Using one equivalent lowered the yield, but minimised bis-adduct formation, which allowed facile purification by short path distillation on larger scales. Compound 8 was functionalised to the tertiary alcohol 9 by a Grignard reaction with MeMgBr, which could be directly cyclised

• -dimethylacryloyl chloride and pyridine provided 12 in good yield (Scheme 5). The acid-catalysed reaction with 12 was predicted to proceed via initial formation of the corresponding tertiary alcohol involving a Markovnikov addition, before cyclisation as with 10. Indeed, cyclisation product 13 (see Supporting

• intermediate 7. Synthesis of THQ 10, by initial aza-Michael addition, followed by formation of the tertiary alcohol 9, which was then cyclised with H2SO4. Synthesis of THQ 14 by initial acylation, cyclisation with H2SO4 and reduction with borane·dimethyl sulphide complex. N-Alkylation of 13 and 14. Facile

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• peroxyester B is initially prepared from a tertiary alcohol A and a peracid. In addition, the peroxy ester can also be prepared via the reaction of a ketone and a peracid (i.e., through a Baeyer–Villiger oxidation); the additional product of peracid to ketone is often referred to as the Criegee intermediate

• feature of the Criegee rearrangement is that the Criegee intermediate rearranges into a carbocation. The mechanism of the Criegee reaction is presented in Scheme 38. Initially the reaction of the peracid with the tertiary alcohol 122 produces perester (Criegee intermediate) 123. One alkyl substituent

Stereoselective synthesis of tricyclic compounds by intramolecular palladium-catalyzed addition of aryl iodides to carbonyl groups

• Jakub Saadi,
• Christoph Bentz,
• Kai Redies,
• Dieter Lentz,
• Reinhold Zimmer and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2016, 12, 1236–1242, doi:10.3762/bjoc.12.118

• –R2 = (CH2)4] typical Heck reaction conditions employing styrene as olefin component not only led to the desired styrene derivative B but mainly to the cyclized product C. If the reaction was performed without the olefin it provided only the tertiary alcohol C in reasonable yield [5]. Similar C–C bond

• determined by an X-ray crystal structure analysis of the corresponding p-nitrobenzoate 12a obtained by esterification of the tertiary alcohol under standard conditions (Scheme 4, Figure 1) [13]. The configuration of the second product 11b is only tentatively assigned as depicted since the available data do

• -iodoaniline derivative to a tricyclic tertiary alcohol as reported by Solé et al. [23]. Proposed transition state (TS) explaining the stereoselective formation of cyclization products. Possible mechanism of the reduction of palladium(II) to palladium(0) by triethylamine (additional ligands at palladium are

NeoPHOX – a structurally tunable ligand system for asymmetric catalysis

• Jaroslav Padevět,
• Marcus G. Schrems,
• Robin Scheil and
• Andreas Pfaltz

Beilstein J. Org. Chem. 2016, 12, 1185–1195, doi:10.3762/bjoc.12.114

• intermediate is a NeoPHOX derivative bearing a methoxycarbonyl group at the stereogenic center next to the oxazoline N atom. The addition of methylmagnesium chloride leads to a tertiary alcohol, which can be acylated or silylated to produce NeoPHOX ligands with different sterical demand. The new NeoPHOX

• -butyl group of tert-leucine, which can be converted to a sterically demanding substituent by double addition of Grignard or alkyllithium reagents and subsequent protection of the resulting tertiary alcohol. An attractive feature of this approach is that by proper choice of the alkylmetal reagent and the

• these conditions, although this method had been successfully used for the alkylation and acylation of the tertiary alcohol function of analogous serine derived PHOX ligands [30]. Among various amines, 2,6-lutidine was finally identified as a suitable base for conversion to the desired derivatives in 67

Studies on the synthesis of peptides containing dehydrovaline and dehydroisoleucine based on copper-mediated enamide formation

• Franziska Gille and
• Andreas Kirschning

Beilstein J. Org. Chem. 2016, 12, 564–570, doi:10.3762/bjoc.12.55

• acids dehydrovaline or dehydroisoleucine, e.g., found in myxovalargin (1), are much more challenging to prepare due to steric hindrance in the β-position and the issue of regiocontrol during elimination [4][5], as β-elimination of a tertiary alcohol group often leads to the terminal instead of the

Recent advances in N-heterocyclic carbene (NHC)-catalysed benzoin reactions

• Rajeev S. Menon,
• Akkattu T. Biju and
• Vijay Nair

Beilstein J. Org. Chem. 2016, 12, 444–461, doi:10.3762/bjoc.12.47

• -aminoketones 39 in high enantioselectivity [41]. Notably, the homoenolate or enolate reactivity of the NHC-enal adduct was not observed in this case. The presence of a tertiary alcohol functionality and the steric bulk of the NHC-precatalyst 40 were essential for the selective formation of the aza-benzoin

Diastereoselective synthesis of new O-alkylated and C-branched inositols and their corresponding fluoro analogues

• Charlotte Collet,
• Françoise Chrétien,
• Yves Chapleur and
• Sandrine Lamandé-Langle

Beilstein J. Org. Chem. 2016, 12, 353–361, doi:10.3762/bjoc.12.39

• rather contradictory concerning the acetylation of this tertiary alcohol using acetic anhydride [50][51]. With regard to a PET application, the protection of this hydroxy group is of paramount importance since the free hydroxy group could impair the incorporation of the radioactive fluorine. Therefor

• several methods of acetylation were carried out on myo-14, which was used as model. The best results for the acetylation of the tertiary alcohol in good yield was obtained with the transesterification method using isopropenyl acetate as acylating agent and p-toluenesulfonic acid as catalyst at 80 °C for 2

• stage. For this, compounds myo-20 and scyllo-20 were reacted with tosyl chloride in the presence of a catalytic amount of triethylamine at room temperature for 3 h to give tosylated myo-22 and scyllo-22 in 70 and 71% yield, respectively. Next, acetylation of the tertiary alcohol was performed before

Synthesis of Xenia diterpenoids and related metabolites isolated from marine organisms

• Tatjana Huber,
• Lara Weisheit and
• Thomas Magauer

Beilstein J. Org. Chem. 2015, 11, 2521–2539, doi:10.3762/bjoc.11.273

• literature-known procedure [47]. Regioselective reduction with sodium borohydride, followed by dehydration under Mitsunobu conditions and silylation of the tertiary alcohol furnished trimethylsiloxy ketone 78. The ketone functionality was then diastereoselectively reduced under Corey–Bakshi–Shibata

Stereoselective synthesis of hernandulcin, peroxylippidulcine A, lippidulcines A, B and C and taste evaluation

• Marco G. Rigamonti and
• Francesco G. Gatti

Beilstein J. Org. Chem. 2015, 11, 2117–2124, doi:10.3762/bjoc.11.228

• ]. Thus, first the tertiary alcohol of 8 was protected as trimethylsilyl ether giving 9 ([α]D −11.5° (c 1.3, CHCl3), vs lit. [13] [α]D −16.3° (c 0.12, EtOH)), which, after treatment with lithium diisopropylamide (LDA) followed by addition of trimethylsilyl chloride (TMSCl) at –78 °C in THF afforded the

• amount of ketone 13 were isolated (Scheme 3). The latter is likely produced by a variant of the Kornblum–DeLaMare rearrangement [34][35] of the O-silyl precursor at room temperature, unfortunately 13 is very unstable. However, we envisaged the possibility of using this ketone, prior its tertiary alcohol

SmI₂-mediated dimerization of indolylbutenones and synthesis of the myxobacterial natural product indiacen B

• Nils Marsch,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2015, 11, 1700–1706, doi:10.3762/bjoc.11.184

• substituents in a cis arrangement and differ regarding the configuration of the tertiary alcohol moiety. Minor bisindolylcyclopentane 8 exhibits a trans arrangement of the indolyl substituents. For the great majority of intermolecular reductive dimerizations of α,β-unsaturated β-arylketones induced by SmI2

• ]. Treatment of indole 14 with SmI2 afforded the cyclic bisindole 15 and, after silica column chromatography, its elimination product cyclopentene 16. On the TLC only the tertiary alcohol 15 and full consumption of the starting material were observed. Product 15 was converted quantitatively to cyclopentene 16

• by treatment with p-TsOH (20 mol %) in chloroform (Scheme 3). As a consequence of smaller ring strain, the double bond is formed in β,γ-position to the carbonyl group. The relative configuration of tertiary alcohol 15 was determined on the basis of NOESY correlations, which revealed that 1-H (4.58

The synthesis of active pharmaceutical ingredients (APIs) using continuous flow chemistry

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2015, 11, 1194–1219, doi:10.3762/bjoc.11.134

• stream of triethylamine in order to promote the elimination of the activated tertiary alcohol. A good isolated yield of (E/Z)-tamoxifen (132) (84%, E/Z ratio 25:75) was achieved after trituration with hot hexanes. As this report states, the peristaltic pumping module used in this synthesis permitted a

Further exploration of the heterocyclic diversity accessible from the allylation chemistry of indigo

• Alireza Shakoori,
• John B. Bremner,
• Mohammed K. Abdel-Hamid,
• Anthony C. Willis,
• Rachada Haritakun and
• Paul A. Keller

Beilstein J. Org. Chem. 2015, 11, 481–492, doi:10.3762/bjoc.11.54

• 9 and 10, while no such product was evident from the reaction with the larger cinnamyl bromide. Minor byproducts isolated were the corresponding N-monoallylated indigos (7–15%). These heterocycles arise from the cyclisation of one allyl unit onto a carbonyl, leading to the tertiary alcohol. They are