Synthesis of (2S,3R)-3-amino-2-hydroxydecanoic acid and its enantiomer: a non-proteinogenic amino acid segment of the linear pentapeptide microginin

• Rajendra S. Rohokale and
• Dilip D. Dhavale

Beilstein J. Org. Chem. 2014, 10, 667–671, doi:10.3762/bjoc.10.59

• ]. While targeting the synthesis of 2a, the Wittig olefination of 3a with n-hexyltriphenylphosphonium bromide and t-BuOK gave olefin 4a as a diasteromeric mixture of Z and E-isomers in the ratio 9.5:0.5 as shown by 1H NMR of the crude product. The catalytic hydrogenation of alkene 4a with 10% Pd/C in

Synthesis of complex intermediates for the study of a dehydratase from borrelidin biosynthesis

• Frank Hahn,
• Nadine Kandziora,
• Steffen Friedrich and
• Peter F. Leadlay

Beilstein J. Org. Chem. 2014, 10, 634–640, doi:10.3762/bjoc.10.55

• allylation as well as an anti-selective aldol reaction. Reference compounds representing the E- and Z-configured double bond isomers as potential products of the dehydratase reaction were obtained from a common precursor aldehyde by Wittig olefination and Still–Gennari olefination. The final deprotection of

• should be accessible from aldehyde 11 through a Horner–Wadsworth–Emmons reaction and the Still–Gennari olefination as well as by a Wittig olefination with stabilised phosphoranes, respectively. The aldehyde 11 should be accessible from the known molecule 13 via 12 [15]. Synthesis of the common precursor

Deoxygenative gem-difluoroolefination of carbonyl compounds with (chlorodifluoromethyl)trimethylsilane and triphenylphosphine

• Fei Wang,
• Lingchun Li,
• Chuanfa Ni and
• Jinbo Hu

Beilstein J. Org. Chem. 2014, 10, 344–351, doi:10.3762/bjoc.10.32

• prepare the ylide intermediate (Scheme 1, reaction 2) [22][23]. Although the difluorocarbene/phosphine procedure for Wittig olefination has been put forward by Fuqua et al. as early as 1964 [19], the formation of difluoromethylene phosphonium ylide in such a way is quite rare [24][25][26]. Established

• ). As determined by 19F NMR, besides the side product (difluoromethyl)triphenylphosponium bromide (δ −127.9, dd, 3JP-F = 80 Hz, 2JF-H = 47 Hz) as reported in the Wittig olefination with FSO2CF2CO2Me [25], a new product which was assigned as difluorinated phosphonium salt 4 (δ −88.8, ddd, 2JF-F = 298 Hz

• . Although a non-activated ketone such as acetophenone is unreactive under similar conditions, activated ketones could undergo this Wittig olefination reaction. Representative results for the olefination at a slightly elevated temperature (80 °C) are shown in Figure 2. A range of aryl trifluoromethyl (6a–d

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

• Buchwald’s procedure for the catalytic asymmetric vinylation of enones [51]. However, the desired vinylated product could not be obtained under the described conditions. An alternative α-formylation/Wittig olefination sequence gave only low yields. O’Brien et al. [41] described the failure of a direct

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

• formal [4 + 3] cycloaddition [82]. Starting from 4-methoxyphenol (90) Friedel–Crafts acylation and cyclization provided bicycle 91. Wittig olefination furnished benzofuran 92. Diazotransfer using p-ABSA yielded the crucial diazo compound 93, which was used in the following enantioselective

• vinylcarbenoid 120, which underwent cyclopropanation with the added olefin 118 to give bicycle 121 in decent yield. Double deprotection followed by selective acetal-protection of the less hindered alcohol and oxidation of the remaining unprotected alcohol moiety led to aldehyde 122. Wittig olefination resulted

• sequence, with concomitant reduction of the ester to give alcohol 200. Oxidation and Wittig olefination gave olefin 201. Lithium bromide exchange followed by 1,2-addition to ketone 202 yielded tricyclic 203, which was immediately subjected to acidic hydrolysis to give the desired tricyclic core skeleton

Garner’s aldehyde as a versatile intermediate in the synthesis of enantiopure natural products

• Mikko Passiniemi and
• Ari M.P. Koskinen

Beilstein J. Org. Chem. 2013, 9, 2641–2659, doi:10.3762/bjoc.9.300

• –Emmons reaction (HWE). The HWE reaction has many advantages over the Wittig olefination. The phosphonate anions tend to be more nucleophilic (less basic) than the corresponding phosphorous ylides. The byproducts, dialkyl phosphates are water soluble and hence easier to remove from the product compared to

The chemistry of isoindole natural products

• Klaus Speck and
• Thomas Magauer

Beilstein J. Org. Chem. 2013, 9, 2048–2078, doi:10.3762/bjoc.9.243

• accomplished within 6 consecutive steps. Generation of the dienamine 244 with pyrrolidine in methanol at 60 °C triggered an intramolecular Diels–Alder reaction to provide the full carbon skeleton 245. The final transformations of the synthesis involved a Wittig olefination of the ketone and a

A concise enantioselective synthesis of the guaiane sesquiterpene (−)-oxyphyllol

• Martin Zahel and
• Peter Metz

Beilstein J. Org. Chem. 2013, 9, 2028–2032, doi:10.3762/bjoc.9.239

• envisaged deoxygenation route (Scheme 2), this key transformation saved 2 steps and paved the way for a final reaction sequence that was based on our synthesis of (−)-englerin A (5) [6]. Thus, Wittig olefination of the acetyl group in 3 afforded the sensitive vinyl epoxide 10 along with some cyclized

An organocatalytic route to 2-heteroarylmethylene decorated N-arylpyrroles

• Alexandre Jean,
• Jérôme Blanchet,
• Jacques Rouden,
• Jacques Maddaluno and
• Michaël De Paolis

Beilstein J. Org. Chem. 2013, 9, 1480–1486, doi:10.3762/bjoc.9.168

• recently described a one-pot organo-catalyzed synthesis of N-heteroarylmethylene pyrrolidines 4 [13] from readily available aldehydes 1 and imine 2 by a sequence of Mannich coupling [14][15][16][17][18][19][20][21][22][23][24], Wittig olefination with phosphonium 3, and proton-mediated hydroamination

• -heteroaromatic scaffolds is reported. Based on the isomerization of pyrrolidines prepared by a simple and efficient sequence of Mannich/Wittig olefination/hydroamination reactions, no oxidant or metallic salts were employed [31]. This study also led us to investigate the feasibility of this process with

Synthesis of the tetracyclic core of Illicium sesquiterpenes using an organocatalyzed asymmetric Robinson annulation

• Lynnie Trzoss,
• Jing Xu,
• Michelle H. Lacoske and
• Emmanuel A. Theodorakis

Beilstein J. Org. Chem. 2013, 9, 1135–1140, doi:10.3762/bjoc.9.126

• dithioketal 14 (86% yield) [72][73][74]. Wittig olefination of the C-1 ketone with methoxymethylenetriphenylphosphine [75] yielded the corresponding enol methyl ether, which was hydrolyzed to the aldehyde under acidic conditions and reduced with NaBH4 to form alcohol 15 with desired diastereoselectivity at

A Wittig-olefination–Claisen-rearrangement approach to the 3-methylquinoline-4-carbaldehyde synthesis

• Mukund G. Kulkarni,
• Mayur P. Desai,
• Deekshaputra R. Birhade,
• Yunus B. Shaikh,
• Ajit N. Dhatrak and
• Ramesh Gannimani

Beilstein J. Org. Chem. 2012, 8, 1725–1729, doi:10.3762/bjoc.8.197

• important 3-methylquinoline-4-carbaldehydes 6a–h from o-nitrobenzaldehydes 1a–h employing a Wittig-olefination–Claisen-rearrangement protocol. The Wittig reaction of o-nitrobenzaldehydes with crotyloxymethylene triphenylphosphorane afforded crotyl vinyl ethers 2a–h, which on heating under reflux in xylene

• -carbaldehydes 6a–h in excellent yields. Therefore, an efficient method was developed for the preparation of 3-methylquinoline-4-carbaldehydes from o-nitrobenzaldehydes in a simple five-step procedure. Keywords: acetal; Claisen rearrangement; oxidative cleavage; ring-closure; Wittig olefination; Introduction

• method for the synthesis of 3-methylquinoline-4-carbaldehyde. It was considered that a properly substituted 2-(2-nitrophenyl)pent-4-enal [25][26][27] could be a fitting intermediate for this purpose. Such an intermediate is easily accessible through the Wittig-olefination–Claisen-rearrangement protocol

Highly selective synthesis of (E)-alkenyl-(pentafluorosulfanyl)benzenes through Horner–Wadsworth–Emmons reaction

• George Iakobson and
• Petr Beier

Beilstein J. Org. Chem. 2012, 8, 1185–1190, doi:10.3762/bjoc.8.131

• reaction is a modification of the Wittig olefination in which a phosphoryl-stabilized carbanion reacts with an aldehyde or ketone to form an alkene and a water-soluble phosphate ester [23][24][25]. In general, this reaction preferentially gives more stable E-disubstituted alkenes, although several

A new phenylethyl alkyl amide from the Ambrostoma quadriimpressum Motschulsky

• Guolei Zhao,
• Chao Yang,
• Bing Li and
• Wujiong Xia

Beilstein J. Org. Chem. 2011, 7, 1342–1346, doi:10.3762/bjoc.7.158

• chain was accomplished by the selective protection of the hydroxy groups and two-time implementation of the Wittig olefination reaction. Keywords: asymmetric synthesis; beetle; fatty acid amide; isolation; Introduction The leaf beetle Ambrostoma quadriimpressum Motschulsky (Coleoptera: Chrysomelidae

• disconnected into two fragments, 2 and 3. The intermediate fragment 2 would be readily prepared from the commercially available ε-caprolactone. The crucial fragment 3 would be constructed from the intermediate 4 through Wittig olefination. The polyhydroxy compound 4 would be obtained from L-glutamic acid by

• , resulted in the deprotection of the TBDPS group. Alternatively, the alcohol 9 could be obtained by reduction with diisobutylaluminium hydride (Dibal-H) in 86% yield, which was then converted to the corresponding aldehyde 10 by oxidation with PCC. Wittig olefination of aldehyde 10 with n

Intraannular photoreactions in pseudo-geminally substituted [2.2]paracyclophanes

• Henning Hopf,
• Vitaly Raev and
• Peter G. Jones

Beilstein J. Org. Chem. 2011, 7, 658–667, doi:10.3762/bjoc.7.78

• trans,trans-10 by a Wittig olefination, appears to be unstable in the solid state at room temperature, but in the refrigerator at −20 °C or in dilute (~0.1 M) solution in dichloromethane or chloroform it can be stored in the dark for at least 3 months without any detectable decomposition or

• product after 2 h of irradiation with a halogen 1 kW lamp, it appeared to be very unstable even below 0 °C, although it was stable enough for NMR identification. Wittig olefination of the irradiated mixture gave the divinylcyclobutane derivative 14 as the sole product and was isolable by column

The preparation of 3-substituted-1,5-dibromopentanes as precursors to heteracyclohexanes

• Bryan Ringstrand,
• Martin Oltmanns,
• Jeffrey A. Batt,
• Aleksandra Jankowiak,
• Richard P. Denicola and
• Piotr Kaszynski

Beilstein J. Org. Chem. 2011, 7, 386–393, doi:10.3762/bjoc.7.49

• addition of a Grignard reagent to tetrahydro-4H-pyran-4-one, elimination of water, and hydrogenation of the olefin (Method 2A). Typical yields for Method 2A range from 20–30% [39][40]. The second route is the Wittig olefination of tetrahydro-4H-pyran-4-one followed by hydrogenation (Method 2B). Yields for

• the Wittig olefination of tetrahydro-4H-pyran-4-one range from 35–75% [41][42][43]. The third route (Method 2C) begins from tetrahydropyran-4-carboxylic acid: The acid chloride is reacted with a Grignard reagent, and the resulting ketone reduced under Wolff–Kischner conditions. Typical yields for this

• , is more general and suitable for large scale synthesis, but involves an additional step. Tetrahydropyrans VIII can be prepared in two steps via Wittig olefination. The efficiency of this method is limited by the initial olefination step of tetrahyro-4H-pyran-4-one, where the yields range from 20–40

Rh-Catalyzed rearrangement of vinylcyclopropane to 1,3-diene units attached to N-heterocycles

• Franca M. Cordero,
• Carolina Vurchio,
• Stefano Cicchi,
• Armin de Meijere and
• Alberto Brandi

Beilstein J. Org. Chem. 2011, 7, 298–303, doi:10.3762/bjoc.7.39

• the construction of other heterocyclic compounds by selective elaboration of the α-oxocyclopropane functionality, for example, to vinylcyclopropane (VCP) by simple Wittig olefination. The rearrangement of VCPs to cyclopentenes and dienes are well known processes [18][19][20][21][22][23][24][25] that

• influence of the N-heterocyclic system on the rearrangement, some model VCPs were generated by Wittig olefination of the α-oxocyclopropane group of functionalized oligocyclic spirocyclopropane-tetrahydropyridones and converted into the corresponding 1,3-dienes by treatment with Rh(PPh3)3Cl. Results and

• File 1 for full experimental data). The two diastereomeric indolizidinones anti-12 and syn-12 are formed by the thermal rearrangement of the cycloadducts anti-(3-t-BuO)-11 and syn-(3-t-BuO)-11, respectively. Wittig olefination of ketones 8, anti-12 and 16 [43] with MePPh3Br/t-BuOK in THF at room

Total synthesis of (±)-coerulescine and (±)-horsfiline

• Mukund G. Kulkarni,
• Attrimuni P. Dhondge,
• Sanjay W. Chavhan,
• Ajit S. Borhade,
• Yunnus B. Shaikh,
• Deekshaputra R. Birhade,
• Mayur P. Desai and
• Nagorao R. Dhatrak

Beilstein J. Org. Chem. 2010, 6, 876–879, doi:10.3762/bjoc.6.103

• Mukund G. Kulkarni Attrimuni P. Dhondge Sanjay W. Chavhan Ajit S. Borhade Yunnus B. Shaikh Deekshaputra R. Birhade Mayur P. Desai Nagorao R. Dhatrak Department of Chemistry, University of Pune, Ganeshkhind, Pune-411 007, Maharashtra, India 10.3762/bjoc.6.103 Abstract Wittig olefination–Claisen

• rearrangement protocol was applied to obtain 3-allyl oxindole. This oxindole was then converted to (±)-coerulescine and (±)-horsfiline. Keywords: alkaloids; Claisen rearrangement; Jones oxidation; spiro-oxindole; Wittig olefination; Introduction The spiro[pyrrolidin-3,3′-oxindole] ring system is a widely

• [31], dimethyldioxirane (DMDO) mediated oxidation [32], and by tandem intramolecular photocycloaddition–retro-Mannich reaction [33]. The Wittig olefination–Claisen rearrangement protocol [35] provides a ready access to 4-pentenals, which have served as versatile intermediates for the synthesis of a

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

An efficient synthesis of tetramic acid derivatives with extended conjugation from L-Ascorbic Acid

• Biswajit K. Singh,
• Surendra S. Bisht and
• Rama P. Tripathi

Beilstein J. Org. Chem. 2006, 2, No. 24, doi:10.1186/1860-5397-2-24

• aldehydes. Wittig olefination followed by reaction of the resulting tetranolactonyl dienyl esters with different amines resulted in the respective 5-hydroxy lactams. Subsequent dehydration of the hydroxy lactams with p-toluene sulphonic acid afforded the dienyl tetramic acid derivatives. All reactions were

• compounds were determined on the basis of their spectroscopic data (Supporting Information File 1). Wittig olefination of aldehydes 7 and 8 with carbethoxymethylene triphenylphosphorane in THF at ambient temperature led to the formation of the respective exo-dienyl esters of the tetronolactones as a mixture

• studies. In such an earlier study, [37] with BuLi at -78°C used as the base for the Wittig olefination, lower yields and poor stereoselection was observed as compared to our uncatalysed ambient temperature reaction where ZZ isomers were predominantly formed. The Z configuration of the allylic alcohol was