p-Nitrophenyl carbonate promoted ring-opening reactions of DBU and DBN affording lactam carbamates

• Madhuri Vangala and
• Ganesh P Shinde

Beilstein J. Org. Chem. 2016, 12, 2086–2092, doi:10.3762/bjoc.12.197

• . To evaluate the substrate feasibility, one phenol, an allylic alcohol and three sugar alcohols were subjected to the reaction. The 3,4-dimethylphenyl p-nitrophenyl carbonate (9a) and geranyl carbonate 10a gave the corresponding γ-lactams 9b and 10b in 62% and 46% yields, respectively. Similarly, the

Selective bromochlorination of a homoallylic alcohol for the total synthesis of (−)-anverene

• Frederick J. Seidl and
• Noah Z. Burns

Beilstein J. Org. Chem. 2016, 12, 1361–1365, doi:10.3762/bjoc.12.129

• unsaturated ester was then reduced with DiBAl–H to allylic alcohol 10, which was isolated as an unchanged 8:1 mixture of regioisomeric bromochlorides, strongly suggesting that no stereochemical or regiochemical isomerization had taken place over the previous three steps from 6. When 10 was subjected to

• two enantiomers (or pseudoenantiomers) of a substrate allylic alcohol. Tetrahalide 11 was then oxidized to the corresponding aldehyde. Installation of the vinyl bromide was found to be difficult using traditional methods. Takai olefination [14] with CHBr3 and CrBr2 resulted in significant de

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

• various test substrates were much lower than those induced by the tert-butyloxazoline analog with the exception of the result obtained with the allylic alcohol S2 (Table 1). Surprisingly, the presence of two geminal phenyl substituents at C(5) had a negative impact on the enantioselectivity, as shown by

Synthesis of a deuterated probe for the confocal Raman microscopy imaging of squalenoyl nanomedicines

• Eric Buchy,
• Branko Vukosavljevic,
• Maike Windbergs,
• Dunja Sobot,
• Camille Dejean,
• Simona Mura,
• Patrick Couvreur and
• Didier Desmaële

Beilstein J. Org. Chem. 2016, 12, 1127–1135, doi:10.3762/bjoc.12.109

• (along with N2 and the trisyl anion) which upon condensation with squalenaldehyde 10 furnished the desired allylic alcohol 16 in 59% yield. Reduction of the hydroxy group of 16 was straightforwardly achieved in 47% yield by treatment with a large excess of thionyl chloride followed by LiAlD4 reduction

• . We next turned to the elaboration of the isopropylidene-d6 moiety. In the event, the Shapiro reaction using trisylhydrazide 14 delivered the expected allylic alcohol 21 in 70% yield. The latter afforded the deuterated ketal 22 in 52% yield, upon sequential treatment with thionyl chloride and LiAlD4

• using the van Tamelen sequence (i. 1 equiv NBS, THF, H2O; ii. K2CO3, MeOH; iii. H3IO6, Et2O) afforded the aldehyde 26 in 16% overall yield. Uneventfully, the Shapiro reaction with trisylhydrazone 14 produced the allylic alcohol 27. Thionyl chloride treatment followed by LiAlD4 reduction delivered

Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(−)-myrtenol nitrate

• Sean P. Bew,
• Glyn D. Hiatt-Gipson,
• Graham P. Mills and
• Claire E. Reeves

Beilstein J. Org. Chem. 2016, 12, 1081–1095, doi:10.3762/bjoc.12.103

• a non-conjugated ‘isolated’ C=C bond, typical of an allylic alcohol, i.e., rac-17 (Scheme 4). Intrigued by the possibility it was the C=C bond of rac-17 that was contributing, in a negative sense, to a poor reaction outcome a ‘compare and contrast study’ using paired-up alcohols, i.e., 34 (4-hydroxy

• efficient separation of (E)-13 and (Z)-14 was not possible without recourse to analytical HPLC [9]. Nevertheless we considered it important to validate our proposed ‘halide for nitrate’ substitution by undertaking a ‘test’ reaction using silver nitrate and the allylic bromide/allylic alcohol mixture (E)-45

• -methoxybenzyloxy)-3-methylbut-2-enyl nitrate (68% yield) as stable, colourless oils. Mild oxidative cleavage of the PMB groups using DDQ in wet DCM generated the desired 1° allylic alcohol (E)-3-methyl-4-hydroxybut-2-enyl nitrate ((E)-11) and (Z)-3-methyl-4-hydroxybut-2-enyl nitrate ((Z)-12) in 62% and 53% yields

Regiodefined synthesis of brominated hydroxyanthraquinones related to proisocrinins

• Joyeeta Roy,
• Tanushree Mal,
• Supriti Jana and
• Dipakranjan Mal

Beilstein J. Org. Chem. 2016, 12, 531–536, doi:10.3762/bjoc.12.52

• lactol 34 with methylmagnesium bromide afforded diol 35 in 72% yield. Selective oxidation of the allylic alcohol group in 35 with MnO2, followed by acetylation of the secondary hydroxy group with acetyl chloride, triethylamine and DMAP furnished cyclohexenone 36 (Scheme 5). The Hauser annulation of

Study on the synthesis of the cyclopenta[f]indole core of raputindole A

• Nils Marsch,
• Mario Kock and
• Thomas Lindel

Beilstein J. Org. Chem. 2016, 12, 334–342, doi:10.3762/bjoc.12.36

• %) was synthesized by Sonogashira coupling of N-TIPS-6-iodoindoline (39) and 42. Conversion of 43 to the (Z)-allylic alcohol 44 by modified (K2CO3) Lindlar hydrogenation (47%) followed. Treatment of 44 with SnCl4 in DCM afforded cyclopenta[f]indoline 45, albeit in the rather disappointing yield of 11%. A

• moderate in both cases (33% and 29%), but already better than in the case of the SnCl4-induced cyclization of (Z)-allylic alcohol 44 (Scheme 6). We only isolated the cyclopentanones, formed from the corresponding cyclopentenyl acetates. Presumably, the propargylacetate first undergoes a [3,3]-sigmatropic

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

• coraxeniolide A (10) [12], starting from chiral (−)-Hajos–Parrish diketone (58) [39]. Based on Pfander's seminal work, the first total synthesis of a xenicane diterpenoid was then accomplished by Leumann in 2000 (Scheme 6) [40]. Starting from enantiopure (−)-Hajos–Parrish diketone (58), allylic alcohol 59 was

• allylic alcohol which was converted to the corresponding para-methoxybenzyl ether 90 using Bundle's reagent [51]. In the key step of the synthesis, the nine-membered carbocyclic ring was constructed via a ring-closing metathesis reaction. Under optimized conditions, Hoveyda–Grubbs second generation

• global reduction of the carbonyl functionalities afforded allylic alcohol 109. The precursor for the key reaction was obtained by formation of the methoxymethyl (MOM) ether from primary alcohol 109 and subsequent conversion of the allylic alcohol to stannane 110. The following 2,3-Wittig–Still

Beyond catalyst deactivation: cross-metathesis involving olefins containing N-heteroaromatics

• Kevin Lafaye,
• Cyril Bosset,
• Lionel Nicolas,
• Amandine Guérinot and
• Janine Cossy

Beilstein J. Org. Chem. 2015, 11, 2223–2241, doi:10.3762/bjoc.11.241

• , biologically relevant conditions were selected (rt, t-BuOH/H2O) and CM involving allyl sulfides that contain functional groups commonly found in DNA-intercalators and N-heteroaromatics were investigated. When a quinoline was present on the allylic sulfide, allylic alcohol was found to be the unique suitable

• partner among the tested olefins. In addition, 20 equiv of allylic alcohol were required and the CM product was obtained in a moderate 53% yield. Cross-metathesis of 81 with amide 83 or alkene 85 gave no conversion (Scheme 32). In the presence of a quinoxaline moiety on the allyl sulfide, the CM reaction

• with allylic alcohol delivered 88 in a low 31% yield and when an alkene containing a phenanthroline was used, no reaction occurred. By the light of the previously reported observations, these results could be imputed to the deactivation of the ruthenium catalyst caused by N-heteroaromatics (Scheme 33

Recent applications of ring-rearrangement metathesis in organic synthesis

• Sambasivarao Kotha,
• Milind Meshram,
• Priti Khedkar,
• Shaibal Banerjee and
• Deepak Deodhar

Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199

• prepared from the corresponding allylic alcohol 63 by esterification with the anhydride 64 derived from cyclobutene. Later, the ester 65, on treatment with the catalyst 1 under toluene reflux conditions followed by treatment with the catalyst 2 furnished the macrolide-butenolides 66 in 42–48% yields via

Preparation of conjugated dienoates with Bestmann ylide: Towards the synthesis of zampanolide and dactylolide using a facile linchpin approach

• Jingjing Wang,
• Samuel Z. Y. Ting and
• Joanne E. Harvey

Beilstein J. Org. Chem. 2015, 11, 1815–1822, doi:10.3762/bjoc.11.197

• oct-2-en-1-ol (9b) with cinnamaldehyde (10a) was efficient and high yielding (Table 1, entry 3). Use of a Z-allylic alcohol 9c, likewise produced excellent amounts of the product dienoate (Table 1, entry 4), although a longer reaction time was required to achieve this. The Z-geometry of the allylic

• alcohol was retained, as expected. After this, the secondary allylic alcohol 9d was investigated and a reasonable yield of the product was obtained when the reaction was carried out in THF (Table 1, entry 5). A comparative reaction in toluene was also performed and found to deliver a better yield of the

Novel carbocationic rearrangements of 1-styrylpropargyl alcohols

• Christine Basmadjian,
• Fan Zhang and
• Laurent Désaubry

Beilstein J. Org. Chem. 2015, 11, 1017–1022, doi:10.3762/bjoc.11.114

• molybdenum(VI)-catalyzed etherification of allylic alcohol with a gold(I)-catalyzed intramolecular cyclization process [5][6]. During the optimization process of this synthesis, we examined several catalysts to transform allylic alcohol 1 into ether 2, including Re2O7, which is described to efficiently

Electrochemical selenium- and iodonium-initiated cyclisation of hydroxy-functionalised 1,4-dienes

• Philipp Röse,
• Steffen Emge,
• Jun-ichi Yoshida and
• Gerhard Hilt

Beilstein J. Org. Chem. 2015, 11, 174–183, doi:10.3762/bjoc.11.18

• -dienols could be generated from simple 1,3-dienes, such as 1,3-butadiene or 1-aryl-substituted 1,3-dienes 1, and TMS-protected allylic alcohol (Scheme 1) for the synthesis of 1,4-dienols of type 2. The cobalt-catalysed hydrovinylation reaction is highly regiospecific for the carbon–carbon bond formation

• ]. The synthesis of the 1,4-dienes was then accomplished utilising the cobalt-catalyst precursor and reducing conditions in the presence of zinc iodide for abstracting the bromide anions at room temperature. The TMS-protected allylic alcohol was applied in the cobalt-catalysed 1,4-hydrovinylation process

• with aryl-substituted 1,3-dienes 1a–k because the use of allylic alcohol itself led to significant lower yields (up to 30%). Only in case of buta-1,3-diene, 2,3-dimethyl-1,3-butadiene and isoprene allyl alcohol could be used directly without decreasing the yield (Table 1, entries 12–14). The results of

A modular phosphate tether-mediated divergent strategy to complex polyols

• Paul R. Hanson,
• Susanthi Jayasinghe,
• Soma Maitra,
• Cornelius N. Ndi and
• Rambabu Chegondi

Beilstein J. Org. Chem. 2014, 10, 2332–2337, doi:10.3762/bjoc.10.242

• partners. In this regard, triene 5 was first subjected to RCM in the presence of the Hoveyda–Grubbs II (HG-II) catalyst [35][36][37] in refluxing CH2Cl2, followed by solvent concentration and CM with allylic alcohol 3 in refluxing CH2Cl2 for two hours. It was observed that the use of CH2Cl2 was critical

• E- and Z-olefin geometries. Triene 5, was subjected to an RCM reaction, followed by a CM reaction with allylic alcohol 3. After removing the solvent, the CM product was treated with LiAlH4 to produce tetraol 12 in 38% yield over three reaction steps in the one-pot, sequential process (73% avg/rxn

• different tetraol 18 was generated in 23% yield over the four reaction steps in a two-pot operation (69% avg/rxn) (Scheme 3). In a similar manner, starting with triene 7, RCM and subsequent CM with allylic alcohol 3, followed by tether removal with LiAlH4, were performed to obtain tetraol 19 in 42% yield

Palladium-catalysed cyclisation of alkenols: Synthesis of oxaheterocycles as core intermediates of natural compounds

• Miroslav Palík,
• Jozef Kožíšek,
• Peter Koóš and
• Tibor Gracza

Beilstein J. Org. Chem. 2014, 10, 2077–2086, doi:10.3762/bjoc.10.216

• DIBAL-H [32] providing the known allylic alcohol in very good yield. Following protection of the primary alcohol yielded fully protected alkene-tetraol and subsequent chemoselective removal of the acetonide protecting group in one pot led to substrates 24–26. The synthesis of substrate 28 bearing a

• tertiary allylic alcohol was performed in a two-step sequence. The addition of methyllithium to ester Z-17 and following deprotection of the corresponding alcohol 27 with aqueous acetic acid afforded tetraol 28 in good yield. Substrates syn-diols 33–35 (not bearing an α-O-protected group) were prepared in

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

• amide 79 not only afforded good E/Z ratios of 87:13 to 88:12 of 73b but also provided a product that could now be separated by column chromatography (Table 1, entries 3 and 4). Reduction of amide E-73b by LiAlH4 to aldehyde 74 and further reduction under Luche conditions delivered an allylic alcohol

Selective allylic hydroxylation of acyclic terpenoids by CYP154E1 from Thermobifida fusca YX

• Anna M. Bogazkaya,
• Clemens J. von Bühler,
• Sebastian Kriening,
• Alexandrine Busch,
• Alexander Seifert,
• Jürgen Pleiss,
• Sabine Laschat and
• Vlada B. Urlacher

Beilstein J. Org. Chem. 2014, 10, 1347–1353, doi:10.3762/bjoc.10.137

• )-19), which was prepared from geraniol (1) in 93% yield [35] was treated under modified Sharpless conditions [36] with a catalytic amount of SeO2 in the presence of t-BuOOH in dichloromethane at 0 °C, to give enal (E)-20 and allylic alcohol (E)-21 in 19% and 45% yield, respectively, which were

• into neryl acetate ((Z)-19) in 87%, followed by allylic oxidation [38], to provide enal (Z)-20 and allylic alcohol (Z)-21 in 14% and 41% yield, respectively. Saponification of 8-hydroxyneryl acetate ((Z)-21) under the above mentioned conditions gave 8-hydroxynerol (4) in 73% yield (Scheme 2). Following

• (2) reached 77%, but was less selective than that of geraniol (1) resulting in the allylic alcohol 8-hydroxynerol (4, 96%) and 2,3-epoxynerol (6, 4%) as byproduct (Table 1). As expected, amino acid substitutions at position 286 changed both regio- and chemoselectivity of the wild type significantly

Synthesis of a sucrose dimer with enone tether; a study on its functionalization

• Zbigniew Pakulski,
• Norbert Gajda,
• Magdalena Jawiczuk,
• Jadwiga Frelek,
• Piotr Cmoch and
• Sławomir Jarosz

Beilstein J. Org. Chem. 2014, 10, 1246–1254, doi:10.3762/bjoc.10.124

• sucrose aldehyde afforded a dimer composed of two sucrose units connected via their C6-positions (‘the glucose ends’). The carbonyl group in this product (enone) was stereoselectively reduced with zinc borohydride and the double bond (after protection of the allylic alcohol formed after reduction) was

• oxidized with osmium tetroxide to a diol. Absolute configurations of the allylic alcohol as well as the diol were determined by circular dichroism (CD) spectroscopy using the in situ dimolybdenum methodology. Keywords: CD-spectroscopy; Cotton effect; multivalent glycosystems; osmylation; stereoselective

• of 10. Indeed, treatment of enone 10 with Zn(BH4)2 under the standard conditions afforded allylic alcohol 11 as single stereoisomer in 65% yield. Based on our model, the R-configuration might be safely assigned to the new stereogenic center. This assignment was further verified independently by

Olefin cross metathesis based de novo synthesis of a partially protected L-amicetose and a fully protected L-cinerulose derivative

• Bernd Schmidt and
• Sylvia Hauke

Beilstein J. Org. Chem. 2014, 10, 1023–1031, doi:10.3762/bjoc.10.102

• Bernd Schmidt Sylvia Hauke Institut für Chemie, Organische Synthesechemie, Universität Potsdam, Karl-Liebknecht-Straße 24–25, 14476 Potsdam-Golm, Germany 10.3762/bjoc.10.102 Abstract Cross metathesis of a lactate derived allylic alcohol and acrolein is the entry point to a de novo synthesis of 4

• ], respectively, which both use enantiomerically pure L-ethyl lactate (1) as the starting material (Scheme 1). The synthetic routes rely on the highly diastereoselective two-step conversion of ethyl lactate to allylic alcohol 2 [36][37] and further to the RCM precursor 3, which then undergoes RCM-isomerization to

• analysis was possible. The data suggest that cinerulose exists in CDCl3 as a 2:1 mixture of acyclic aldose 27 and lactol 28 (Scheme 5). Conclusion In summary, we showed that an allylic alcohol, available diastereoselectively from enantiomerically pure L-lactate in few steps, is a useful starting material

Structure elucidation of female-specific volatiles released by the parasitoid wasp Trichogramma turkestanica (Hymenoptera: Trichogrammatidae)

• Armin Tröger,
• Teris A. van Beek,
• Martinus E. Huigens,
• Isabel M. M. S. Silva,
• Maarten A. Posthumus and
• Wittko Francke

Beilstein J. Org. Chem. 2014, 10, 767–773, doi:10.3762/bjoc.10.72

• identified as the hydrocarbon 2,6,8,12-tetramethyltrideca-2,4-diene (A) and the corresponding allylic alcohol 2,6,8,12-tetramethyltrideca-2,4-diene-1-ol (B) [12]. Since the two proposed structures were deduced from analytical data only, the aim of the present study was to scrutinize these suggestions by

Asymmetric total synthesis of a putative sex pheromone component from the parasitoid wasp Trichogramma turkestanica

• Danny Geerdink,
• Jeffrey Buter,
• Teris A. van Beek and
• Adriaan J. Minnaard

Beilstein J. Org. Chem. 2014, 10, 761–766, doi:10.3762/bjoc.10.71

• allylic alcohol 17 in 90% yield, which in turn was oxidized to aldehyde 18 using Dess–Martin periodinane. Given that the conversion of 18 into 19 using a Wittig reaction had proven to be sluggish, we switched again to a Horner–Wadsworth–Emmons olefination, expecting to observe high E-selectivity. Indeed

Efficient carbon-Ferrier rearrangement on glycals mediated by ceric ammonium nitrate: Application to the synthesis of 2-deoxy-2-amino-C-glycoside

• Alafia A. Ansari,
• Y. Suman Reddy and
• Yashwant D. Vankar

Beilstein J. Org. Chem. 2014, 10, 300–306, doi:10.3762/bjoc.10.27

• of a sharp singlet at δ 2.11, corresponding to methyl protons in the 1H NMR spectrum, as well as a peak at δ 207 ppm in the 13C NMR spectrum corresponding to the carbonyl group (see Supporting Information File 1). The allylic alcohol 9 was converted to the corresponding trichloroacetimidate, which in

Synthesis of the B-seco limonoid core scaffold

• Hanna Bruss,
• Hannah Schuster,
• Rémi Martinez,
• Markus Kaiser,
• Andrey P. Antonchick and
• Herbert Waldmann

Beilstein J. Org. Chem. 2014, 10, 194–208, doi:10.3762/bjoc.10.15

• intended rearrangement with one of the model C rings. Thus carboxylic acid 87 was esterified with allylic alcohol 40 to give allyl ester 88 (Scheme 13). Unfortunately exposure of 88 to the optimized conditions developed for the synthesis of the B-seco limonoid scaffold did not initiate the desired Ireland

Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis

• Sebastian Krüger and
• Tanja Gaich

Beilstein J. Org. Chem. 2014, 10, 163–193, doi:10.3762/bjoc.10.14

• to give pentacycle 172. Reduction of the nitro group was followed by Cbz-protection. Allylic alcohol 173 resulted from radical allylic bromination followed by displacement of bromine through water under silver-catalysis. Eschenmoser–Claisen rearrangement [148] led to the formation of the remaining

• Iguchi and co-workers [44] applied the DVCPR to the total synthesis of the marine prostanoid clavubicyclone [45]. Known aldehyde 33 (see Scheme 7) [46] was subjected to Wittig conditions to furnish an intermediate lactone, which was then opened reductively followed by selective oxidation of the allylic

• alcohol to yield aldehyde 34. Addition of double deprotonated methyl acetoacetate gave β-ketoester 35. Diazotransfer followed by double protection resulted in the formation of compound 36. Rh-catalyzed intramolecular cyclopropanation of this compound gave bicycle 37. Selective removal of the secondary

A unified approach to the important protein kinase inhibitor balanol and a proposed analogue

• Tapan Saha,
• Ratnava Maitra and
• Shital K. Chattopadhyay

Beilstein J. Org. Chem. 2013, 9, 2910–2915, doi:10.3762/bjoc.9.327

• unified precursor of balanol (1) and an azepin ring-modified balanol 3. Derivative 4 could be obtained through esterification between the carboxylic acid 5 and the allylic alcohol 6. We thus focused on the synthesis of the two key fragments 5 and 6. The synthesis of the benzophenone unit has previously

• . The esterification of the allylic alcohol 29 with the acid 7 (Scheme 3) proceeded best in the presence of Mukaiyama’s reagent [66], 2-chloro-1-methylpyridinium iodide, to provide the ester 31 in 73% yield. Simultaneous hydrogenolytic removal of the O-benzyl groups and the N-Cbz group under reported