- A synthesis method of diol
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The present invention belongs to the field of organic synthesis technology, specifically a synthesis method of a diol; the present invention by bis (trimethylsilyl) lithium amino catalytic lactone boronization of lactone to synthesize a variety of structure of the diol compound; specifically, under the bis (trimethylsilyl) amino lithium catalytic system, to a variety of lactone compounds and pinacol borane as raw materials, the preparation of diol compounds; the method of the present invention raw materials are of a wide range of sources or easy to prepare, easy to operate, selective and controllable, high yield, mild conditions, universality wide.
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Paragraph 0025-0030
(2022/01/12)
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- A phosphine-free iron complex-catalyzed synthesis of cycloalkanes: Via the borrowing hydrogen strategy
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Herein we report a diaminocyclopentadienone iron tricarbonyl complex catalyzed synthesis of substituted cyclopentane, cyclohexane and cycloheptane compounds using the borrowing hydrogen strategy in the presence of various substituted primary and secondary 1,n diols as alkylating reagents. Deuterium labeling experiments confirm that the diols were the hydride source in this cascade process. This journal is
- Bettoni, Léo,Gaillard, Sylvain,Renaud, Jean-Luc
-
supporting information
p. 12909 - 12912
(2020/11/07)
-
- IDO/TDO Inhibitor
-
A compound of formula (I) given below or a pharmaceutically acceptable salt of the compound is useful as an IDO/TDO inhibitor. Thus, the compound of formula (I) or the pharmaceutically acceptable salt of the compound can be used as, for example, a therapeutic agent for a disease or a disorder selected from tumor, infectious disease, neurodegenerative disorder, cataract, organ transplant rejection, autoimmune disease, postoperative cognitive impairment, and disease related to women's reproductive health [in the following formula (I), ring A represents an aromatic ring, an aliphatic ring, a heterocyclic ring, or a condensed ring of two or more rings selected from an aromatic ring, an aliphatic ring and a heterocyclic ring; X, R1 and R2 represent a substituent on a ring atom constituting ring A; m represents an integer of 0 to 6; X represents, for example, a halogen atom; and R1 and R2 are the same or different and are selected from, for example, the group consisting of groups of formula (a) or formula (b); and in the following formula (a) and formula (b), Y is selected from the group consisting of O, S, and Se, Z is selected from the group consisting of O, S, and Se, n represents an integer of 1 to 8, r represents an integer of 1 to 8, s represents an integer of 1 to 8, R4 represents, for example, —C(═NH)—HN2, and R6 represents, for example, a substituted or unsubstituted aryl group].
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Paragraph 0334-0336; 0585-0587
(2020/08/19)
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- A Spiroalkylation Method for the Stereoselective Construction of α-Quaternary Carbons and Its Application to the Total Synthesis of (R)-Puraquinonic Acid
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Cyclic α-quaternary carbon stereocenters were prepared from biselectrophillic substrates and an easily prepared chiral bicyclic sulfonyl lactam. This was achieved in two steps by spiroalkylation, employing biphasic reaction conditions with a phase-transfer catalyst, followed by reduction and alkylation with a series of alkyl halide electrophiles. The products of this method were isolated in good yields with with high levels of diastereoselectivity. This methodology was employed in the enantioselective total synthesis of (R)-puraquinonic acid (1) for a late-stage installation of the α-quaternary carbon stereocenter. This enabled the shortest synthesis of 1 to date, an eight-pot sequence providing an overall yield of 14%.
- Elmehriki, Adam A. H.,Gleason, James L.
-
supporting information
p. 9729 - 9733
(2019/12/02)
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- Stereoselective synthesis of alicyclic ketones: A hydrogen borrowing approach
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A highly diastereoselective annulation strategy for the synthesis of alicyclic ketones from diols and pentamethylacetophenone is described. This process is mediated by a commercially available iridium(III) catalyst, and provides efficient access to a wide range of cyclopentane and cyclohexane products with high levels of stereoselectivity. The origins of diastereoselectivity in the annulation reaction have been explored by a series of control experiments, which provides an explanation for how each stereocentre around the newly forged ring is controlled.
- Armstrong, Roly J.,Akhtar, Wasim M.,Frost, James R.,Christensen, Kirsten E.,Stevenson, Neil G.,Donohoe, Timothy J.
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supporting information
(2019/11/13)
-
- Method for preparing alcoholic compound from anilino lithium compound as catalyst
-
The invention relates to an application of an anilino lithium compound, in particular to a method for preparing an alcoholic compound from the anilino lithium compound as a catalyst. The catalyst, borane and carboxylic acid are stirred and mixed uniformly, subjected to a reaction and exposed to air to terminate the reaction, a reacted liquid is subjected to reduced-pressure treatment for solvent removal, silica gel and methanol are added, and the alcoholic compound is obtained by hydrolysis. The anilino lithium compound can perform high-activity catalysis on the reaction between carboxylic acid and borane at room temperature, dose of the catalyst is only 0.8mol% of the mole ratio of carboxylic acid, compared with the conventional catalysis system, the commercial reagent anilino lithium compound is used, reaction conditions are mild, and yield of borate with different substituents under limit conditions can reach 90% or higher.
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- Synthesis of 1,2-phenylenedimethanols by base-promoted reduction of isobenzofuran-1(3H)-ones with silane
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An efficient method for preparation of substituted 1,2-phenylenedimethanols and aliphatic 1,4-diols that are valuable intermediates in organic synthesis, has been developed by the base-promoted reduction of isobenzofuran-1(3H)-ones and γ-lactones with silane under mild conditions. Compared with traditional procedures using stoichiometric amounts of metal hydrides and alkyl reductants, the present method avoids the use of sensitive reagents and is operationally simple and a broad variety of functional groups are tolerated.
- Liu, Bin,Zhou, Xigeng
-
supporting information
p. 725 - 728
(2018/12/11)
-
- Sulfones as Synthetic Linchpins: Transition-Metal-Free sp3–sp2 and sp2–sp2 Cross-Couplings Between Geminal Bis(sulfones) and Organolithium Compounds
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A valuable umpolung strategy that highlights the ambiphilic nature of the bis(phenylsulfonyl)methyl synthon and demonstrates its utility as a synthetic linchpin is reported. Although the bis(phenylsulfonyl)methyl group is typically introduced as an sp3-carbon nucleophile, it is demonstrated that it can also function as an effective sp2-carbon electrophile in the presence of organolithium nucleophiles. Alkyl- and aryllithiums couple with the central carbon of the bis(phenylsulfonyl)methyl unit to ultimately generate trisubstituted alkenes, comprising formal sp3–sp2 and sp2–sp2 cross-couplings between organolithium reagents and bis(sulfones). This process occurs almost instantaneously at ?78 °C in the absence of any transition metals. By developing this curious transformation, it has been demonstrated that bis(phenylsulfonyl)methane is a valuable synthetic linchpin, which can undergo two C?C bond-forming processes as an sp3-nucleophile, followed by a third C?C bond-forming reaction as an effective sp2-electrophile. This discovery significantly enhances the utility of this ubiquitous, but underutilized, linker group.
- Trost, Barry M.,Kalnmals, Christopher A.
-
supporting information
p. 9066 - 9074
(2018/06/29)
-
- Cyclic ether synthesis from diols using trimethyl phosphate
-
Cyclic ethers have been effectively synthesized via the intramolecular cyclization of diols using trimethyl phosphate and NaH. The present cyclization could proceed at room temperature to produce 5-7 membered cyclic ethers in good to excellent yields. Substrates possessing a chiral secondary hydroxy group were transformed into the corresponding chiral cyclic ethers along with the retention of their stereochemistries.
- Asai, Shota,Kato, Maho,Monguchi, Yasunari,Sajiki, Hironao,Sawama, Yoshinari
-
supporting information
p. 4787 - 4790
(2017/07/06)
-
- Iron(II) pincer-catalyzed synthesis of lactones and lactams through a versatile dehydrogenative domino sequence
-
The synthesis of lactones and lactams by using iron(II) pincer-catalyzed dehydrogenative methodology was developed. Starting from 1,n-diols or 1,n-amino alcohols, this domino transformation takes place through initial dehydrogenation of the substrates, subsequent intramolecular cyclization, and final oxidation to afford the desired products in good yields. The ability to access heterocycles of different sizes makes this protocol especially versatile, in which two consecutive oxidation reactions are performed without requiring an external oxidant. In this paper, we report the application of the Fe-MACHO-BH complex [carbonylhydrido(tetrahydroborato)[bis(2-diisopropylphosphinoethyl)amino]iron(II)] in this atom-efficient and environmentally benign process, for which molecular hydrogen is formed as the only stoichiometric side product. Just a little pinch: The iron(II) pincer-catalyzed synthesis of lactones and lactams from easily available 1,n-diols and 1,n-amino alcohols is explored. The use of a nontoxic metal as well as the generation of molecular hydrogen as the only stoichiometric byproduct makes this method a highly atom-efficient and environmentally benign process.
- Pea-Lpez, Miguel,Neumann, Helfried,Beller, Matthias
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p. 865 - 871
(2015/03/14)
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- POLYNUCLEOTIDE CONSTRUCTS HAVING DISULFIDE GROUPS
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The invention features polynucleotide constructs containing one or more components (i) containing a disulfide linkage, where each of the one or more components is attached to an internudeotide bridging group or a terminal group of the polynucleotide construct, and each of the one or more components (i) contains one or more bulky groups proximal to the disulfide group. The invention also features polynucleotide constructs containing one or more components (i) containing a disulfide linkage, where each of the one or more components (i) is attached to an internudeotide bridging group or a terminal group of the polynucleotide construct, and each of the one or more components (i) contains at least 4 atoms in a chain between the disulfide linkage and the phosphorus atom of the internudeotide bridging group or the terminal group; and where the chain does not contain a phosphate, an amide, an ester, or an alkenylene. The invention also features methods of delivering a polynucleotide to a cell using the polynucleotide constructs of the invention.
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Page/Page column 101
(2015/05/26)
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- POLYNUCLEOTIDE CONSTRUCTS HAVING BIOREVERSIBLE AND NON-BIOREVERSIBLE GROUPS
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The invention features a hybridized polynucleotide construct containing a passenger strand, a guide strand loadable into a RISC complex, and (i) a 3'-terminal or an internucleotide non-bioreversible group in the guide strand; or (ii) a 5'-terminal, a 3'-terminal, or an internucleotide non-bioreversible group in the passenger strand, and a 5'-terminal, a 3'-terminal, or an internucleotide disulfide bioreversible group in the guide strand or the passenger strand. The invention also features methods of delivering a polynucleotide to a cell using the hybridized polynucleotide construct. The invention further features methods of reducing the expression of a polypeptide in a cell using the hybridized polynucleotide construct.
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Page/Page column 89
(2016/02/19)
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- Reactivity of hydroxy- and aquo(hydroxy)-λ3-iodane-crown ether complexes
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We have designed a series of hydroxy(aryl)-λ3-iodane-[18] crown-6 complexes, prepared from the corresponding iodosylbenzene derivatives and superacids in the presence of [18]crown-6, and have investigated their reactivities in aqueous media. These activated iodosylbenzene monomers are all non-hygroscopic shelf-storable reagents, but they maintain high oxidizing ability in water. The complexes are effective for the oxidation of phenols, sulfides, olefins, silyl enol ethers, and alkyl(trifluoro)borates under mild conditions. Furthermore, hydroxy-λ3-iodane-[18]crown-6 complexes serve as efficient progenitors for the synthesis of diaryl-, vinyl-, and alkynyl-λ3-iodanes in water. Other less polar organic solvents, such as methanol, acetonitrile, and dichloromethane, are also usable in some cases. Aqua-friendly iodosylbenzene equivalents: Hydroxy- and aquo(hydroxy)-λ3-iodane-[18]crown-6 complexes (see graphic), readily prepared from commercial PhI(OAc)2 or PhIO, serve as excellent oxygen atom donors toward olefins, phenols, sulfides, and alkyl(trifluoro)borates. They also serve as progenitors for diaryl-, vinyl-, and alkynyl-λ3-iodane-[18]crown-6 complexes. These reactions can be carried out in aqueous media under mild reaction conditions.
- Miyamoto, Kazunori,Yokota, Yukie,Suefuji, Takashi,Yamaguchi, Kentaro,Ozawa, Tomoyuki,Ochiai, Masahito
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p. 5447 - 5453
(2014/05/20)
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- Ketyl-type radicals from cyclic and acyclic esters are stabilized by SmI2(H2O)n: the role of SmI2(H 2O)n in post-electron transfer steps
-
Mechanistic details pertaining to the SmI2-H2O- mediated reduction and reductive coupling of 6-membered lactones, the first class of simple unactivated carboxylic acid derivatives that had long been thought to lie outside the reducing range of SmI2, have been elucidated. Our results provide new experimental evidence that water enables the productive electron transfer from Sm(II) by stabilization of the radical anion intermediate rather than by solely promoting the first electron transfer as originally proposed. Notably, these studies suggest that all reactions involving the generation of ketyl-type radicals with SmI2 occur under a unified mechanism based on the thermodynamic control of the second electron transfer step, thus providing a blueprint for the development of a broad range of novel chemoselective transformations via open-shell electron pathways.
- Szostak, Michal,Spain, Malcolm,Procter, David J.
-
supporting information
p. 8459 - 8466
(2014/06/24)
-
- A facile synthesis of 5,6-dihydro-4H-pyrrolo[3,4-d]thiazole and other pyrrolidine-fused aromatic ring systems via one-step cyclization from diols
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A facile synthetic method of 5,6-dihydro-4H-pyrrolo[3,4-d]thiazole, which is a subunit of a potent factor Xa (fXa) inhibitor was developed. This new approach employs one-step cyclization from a diol and can be applied to the syntheses of other pyrrolidine-fused aromatic ring sytems.
- Yoshikawa, Kenji,Nagata, Tsutomu,Yoshino, Toshiharu,Nakamoto, Yumi,Haginoya, Noriyasu,Muto, Ryo,Mochizuki, Akiyoshi,Kanno, Hideyuki,Ohta, Toshiharu
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experimental part
p. 1711 - 1720
(2012/09/07)
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- Preparation of samarium(II) iodide: Quantitative evaluation of the effect of water, oxygen, and peroxide content, preparative methods, and the activation of samarium metal
-
Samarium(II) iodide (SmI2) is one of the most important reducing agents in organic synthesis. Synthetic chemistry promoted by SmI2 depends on the efficient and reliable preparation of the reagent. Unfortunately, users can experience difficulties preparing the reagent, and this has prevented realization of the full synthetic potential of SmI2. To provide synthetic chemists with general and reliable methods for the preparation of SmI2, a systematic evaluation of the factors involved in its synthesis has been carried out. Our studies confirm that SmI2 is a user-friendly reagent. Factors such as water, oxygen, and peroxide content in THF have little influence on the synthesis of SmI2. In addition, the use of specialized glovebox equipment or Schlenk techniques is not required for the preparation of SmI2. However, our studies suggest that the quality of samarium metal is an important factor and that the use of low quality metal is the main cause of failed preparations of the reagent. Accordingly, we report a straightforward method for activation of "inactive" samarium metal and demonstrate the broad utility of this protocol through the electron transfer reductions of a range of substrates using SmI2 prepared from otherwise "inactive" metal. An investigation into the stability of SmI2 solutions and an evaluation of commercially available solutions of the reagent is also reported.
- Szostak, Michal,Spain, Malcolm,Procter, David J.
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experimental part
p. 3049 - 3059
(2012/06/01)
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- Highly practical copper(I)/TEMPO catalyst system for chemoselective aerobic oxidation of primary alcohols
-
Aerobic oxidation reactions have been the focus of considerable attention, but their use in mainstream organic chemistry has been constrained by limitations in their synthetic scope and by practical factors, such as the use of pure O2 as the oxidant or complex catalyst synthesis. Here, we report a new (bpy)CuI/TEMPO catalyst system that enables efficient and selective aerobic oxidation of a broad range of primary alcohols, including allylic, benzylic, and aliphatic derivatives, to the corresponding aldehydes using readily available reagents, at room temperature with ambient air as the oxidant. The catalyst system is compatible with a wide range of functional groups and the high selectivity for 1° alcohols enables selective oxidation of diols that lack protecting groups.
- Hoover, Jessica M.,Stahl, Shannon S.
-
supporting information; experimental part
p. 16901 - 16910
(2011/12/04)
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- INHIBITORS OF BETA-SECRETASE
-
The present invention is directed to a compound represented by the following structural formula or a pharmaceutically acceptable salt thereof. Pharmaceutical compositions and method of use of the compounds are also described.
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Page/Page column 75
(2010/10/03)
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- BEZOTHIAZOL DERIVATIVES AS BETA2 ADRENORECEPTOR AGONISTS
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The present invention relates to compounds according to formula (I) , a process for preparing them, the intermediate compounds of the process and the use of the compounds in the manufacture of a medicament for use in treating diseases such as ARDS, pulmonary emphysema, bronchitis, bronchiectasis, COPD, asthma and rhinitis. The compounds are beta2 adrenoreceptor agonists.
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Page/Page column 79
(2008/06/13)
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- Activated iodosylbenzene monomer as an ozone equivalent: Oxidative cleavage of carbon-carbon double bonds in the presence of water
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Reported here for the first time are the developments of an efficient method for oxidative cleavage of carbon-carbon double bonds yielding carbonyl compounds by using aryl-λ3-iodanes, which involve a combination of iodosylbenzene and HBF4 in the presence of water. The method serves as a safety alternative to ozonolysis. The oxidative cleavage of olefins probably involves the hitherto unknown direct vicinal dihydroxylations of double bonds with aryl-λ3-iodanes and the subsequent oxidative glycol fissions. Cyclic (cyclopentenes, cyclohexenes, etc.) and acyclic olefins are cleaved smoothly under our conditions. In the reaction of electron-deficient styrenes such as m-nitrostyrene, intermediate formation of the corresponding epoxide was detected. A variety of aryloxiranes also undergo an oxidative cleavage of the epoxide rings under our conditions, and aromatic aldehydes were obtained in good yields. Copyright
- Miyamoto, Kazunori,Tada, Norihiro,Ochiai, Masahito
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p. 2772 - 2773
(2007/10/03)
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- Cp*Ir complex-catalyzed N-heterocyclization of primary amines with diols: A new catalytic system for environmentally benign synthesis of cyclic amines
-
(Chemical Equation Presented) A new efficient method for the N-heterocyclization of primary amines with diols catalyzed by a Cp*Ir complex was developed. A variety of five-, six-, and seven-membered cyclic amines were synthesized in good to excellent yields with the formation of only water as a byproduct. A two-step asymmetric synthesis of (S)-2-phenylpiperidine was also achieved using (R)-1-phenylethylamine as a starting primary amine.
- Fujita, Ken-Ichi,Fujii, Takeshi,Yamaguchi, Ryohei
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p. 3525 - 3528
(2007/10/03)
-
- Synthesis of (+)-(R)-methyl 2-aminotetraline-2-carboxylate: The hydroxypinanone method versus the bislactim method
-
The methyl ester of 2-aminotetraline-2-carboxylic acid (Atc-OMe), an important residue for modified peptides, could only be synthesized from the Schoellkopf bislactim method, the hydroxypinanone method leading, during the second step, to elimination inste
- Solladie-Cavallo, Arlette,Martin-Cabrejas, Luisa M.,Caravatti, Giorgio,Lang, Marc
-
p. 967 - 969
(2007/10/03)
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- MERCAPTOACETYLAMIDO 1,3,4,5-TETRAHYDRO-BENZO[C]AZEPIN-3-ONE DISULFIDE DERIVATIVES USEFUL AS INHIBITORS OF ENKEPHALINASE AND ACE
-
The present invention relates to certain novel mercaptoacetylamido 1,3, 4,5-tetrahydro-benzo[c]azepin-3-one disulfide derivatives of the formula STR1 useful as inhibitors of enkephalinase and of ACE.
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-
-
- Prostaglandin analogs
-
Thromboxane receptor antagonist activity is exhibited by compounds of the formula STR1 wherein: V is --(CH 2) m --, --O--, or STR2 but if V is --O--or STR3 R 3 and R 4 must complete an aromatic ring; W is --(CH 2) 2 --, --CH CH-- or phenylene;X is a single bond, --CH CH--, --(CH 2) n --, or --O--(CH 2) n --; or X is branched alkylene or --O--branched alkylene wherein W is linked to Y through a chain n carbon atoms long;Y is --CO 2 H, --CO 2 alkyl, --CO 2 alkali metal, --CH 2 OH, --CONHSO 2 R 5, --CONHR 6, or --CH 2 -5-tetrazolyl;Z is O or NH;R 3 and R 4 are each independently hydrogen or alkyl or R 3 and R 4 together complete a ring optionally substituted through a ring carbon with a halo, lower alkyl, phenyl, halo (lower alkyl), halophenyl, oxo or hydroxyl group; and the remaining symbols are as defined in the specification.
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- 7-Spirobenzocyclohexyl derivatives of naltrexone, oxymorphone, and hydromorphone as selective opioid receptor ligands
-
On the basis of previous structure-activity studies of the highly potent and selective δ-opioid receptor antagonist naltrindole (1) and the spiroindanyl analagues 2 and 3, we have synthesized epimeric pairs of spirobenzocyclohexyl derivatives of naltrexon
- Fang, Xinqin,Larson, Dennis L.,Portoghese, Philip S.
-
p. 3064 - 3070
(2007/10/03)
-
- The synthesis of aminobenzazepinones as anti-phenylalanine dipeptide mimics and their use in NEP inhibition
-
A general and stereoselective synthesis of 4-aminobenzazepinones is presented. This peptidomimetic structure was used in the preparation of MDL 100,407, a potent inhibitor of NEP.
- Warshawsky, Alan M.,Flynn, Gary A.,Koehl, Jack R.,Mehdi, Shujaath,Vaz, Roy J.
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p. 957 - 962
(2007/10/03)
-
- Electroreduction of Organic Compounds, 19. Formation of Benzoanellated Sulfur Heterocycles by Intramolecular Cathodic Cyclization of Dithiocarboxylic Esters
-
Cathodic reduction of aryl (3) and benzyl (5) dithiopivaloates and related dithioesters with leaving groups at the benzene ring or a side chain yield the sulfur heterocycles 23, 30 - 32, and 34 depending on the nature of the starting material and the reaction conditions.In the case of the α-oxo-dithioester 22, thioindigo (44) is formed. - The corresponding thioamides 14, 16, and 18 show a strong tendency to reductive dehalogenation but the S,N-heterocycles 38 and 39 are also formed in minor amounts. - The formation of the rearranged products 29 - 32, and 34 isdiscussed in terms of C,S-splitting in the primarily formed radical anion and subsequent C,C-coupling of the fragments and follow-up reactions.Key Words: Dithiopivaloates, S-aryl, S-benzyl / Electroreduction
- Gade, Thomas,Streek, Michael,Voss, Juergen
-
p. 127 - 142
(2007/10/02)
-
- DIASTEREO- AND ENANTIOSELECTIVE SYNTHESIS OF 1,2-DIOLS BY VANADIUM(II) PROMOTED PINACOL CROSS COUPLING
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The V(II) promoted pinacol cross coupling of a chiral aromatic aldehyde with achiral aliphatic aldehydes occurs to afford syn diols in up to 91:9 diastereoisomeric ratio and up to 84percent enantiomeric excess.The pinacol coupling of (S)-lactaldehyde and (R)-glyceraldehyde derivatives has also been studied and matching and mis-matching pairs have been identified.The stereochemistry of the products was established by correlation.The sense and degree of stereoselection is discussed.
- Annunziata, Rita,Cinquini, Mauro,Cozzi, Franco,Giaroni, Paola,Benaglia, Maurizio
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p. 5737 - 5758
(2007/10/02)
-
- Synthesis of 3,9b-Dihydro-5H-pyrroloisoindoles and 3,5,6,10b-Tetrahydropyrroloisoquinolines with 1,3-Dipolar Cycloaddition Reactions.
-
The title classes of compounds have been prepared using a sequence of two ring-forming reactions.Initial 1,3-dipolar cycloaddition with an azomethine ylide gave N-acylated 3-pyrrolines which were further elaborated to the target compounds by a tandem deprotection/cyclization reaction.
- Anderson, Wayne K.,Kinder, Frederick R.
-
p. 975 - 979
(2007/10/02)
-
- Carbenes and the O-H Bond: Hydroxyalkyl-Substituted Arylcarbenes
-
carbene (4), phenylcarbene (19), and carbene (30) have been generated by photolysis of tosylhydrazone or diazo precursors in protic solvents.These carbenes give cyclic ethers (7, 18, 33) competitively with insertion into O-H bonds of the solvent.For comparison, the analogous benzyl cations (9, 17, 31) have been generated by solvolysis or dediazoniation.The cations are more sensitive to structural variation than their carbenic counterparts: 9 does not undergo intramolecular nucleophilic substitution, in contrast to 17 and 31.These observations are explicable in terms of high barriers for rotation about aryl-cation bonds, as compared with low barriers for rotation about aryl-carbene bonds.Two major effects of the solvent (ROH) and of the base (RONa) on product formation may be distinguished: (i) protonation of the carbene (or of its precursors) in the more acidic media leads to predominantly cationic processes; (ii) deprotonation of the OH group under strongly basic conditions enhances the nucleophilicity of the oxygen, and also facilitates insertion into the α-C-H bonds of 30.
- Kirmse, Wolfgang,Kund, Klaus
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p. 2325 - 2332
(2007/10/02)
-
- Synthesis of the Benzotricyclo2,7>heptene Ring System via the Intramolecular -Cycloaddition Reaction of Some Cyclopropene Derivatives
-
The photo and thermal reactions of a number of 1,2-diphenyl-3-methyl-3-(o-vinylphenyl)-substituted cyclopropenes have been studied.The thermolysis of these systems gave substituted benzotricyclo2,7> heptenes in good yield by means of a novel intramolecular cycloaddition.The sensitized di-?-methane photorearrangement of several substituted benzonorbornenes was used to independently synthesize the thermal cycloadducts.The observed regiospecificity of the rearrangement is understandable in terms of formation of the most stable diradical intermediate.In contrast to the thermal results, the photosensitized irradiation afforded a mixture of two products.In addition to the cycloadduct, a new compound was isolated whose formation involves attack of the ortho position of the triplet state on the terminal vinyl carbon followed by diradical coupling and subsequent rearomatization.Thermolysis or sensitized photolysis of several unsymmetrically substituted 1,3-diphenyl-2-methyl-2-(o-vinylphenyl)cyclopropenes afforded related cycloadducts.With these systems, the -cycloaddition reaction is highly regiospecific and involves bonding from the cyclopropene carbon bearing the methyl group onto the terminal vinyl carbon.The silver ion and singlet excited-state behavior of several substituted cyclopropenes was also studied, and the results obtained were compared to the reactions which occur on thermolysis or sensitized photolysis.
- Padwa, Albert,Rieker, William F.,Rosenthal, Robert J.
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p. 4446 - 4456
(2007/10/02)
-
- Mechanism of the Reaction between Benzylmagnesium Chloride and Carbonyl Compounds. A Detailed Study with Formaldehyde
-
The reaction of benzylmagnesium chloride in THF with monomeric formaldehyde has been studied in detail.A mechanism is presented which accounts for the formation of the products, 2-phenylethanol, o-tolylcarbinol, and o-(2-hydroxyethyl)benzyl alcohol.A change in technique for Grignard titration and formaldehyde addition results in a much-improved mass balance than achieved previously.The decreased yield of the major product, o-tolylcarbinol, with increased reaction time is explained in terms of a hitherto unsuspected equilibrium influenced by the polymerization of monomeric formaldehyde.An intermediate organometallic species which could lead to some of the diol product, o-(2-hydroxyethyl)benzyl alcohol can be trapped as the trimethylsilyl derivative, but the quantity is insufficient to account for the amount of diol when an excess of formaldehyde is employed.An ene or Prins reaction is invoked for the formation of most of the diol.Deuterium tracer studies suggest competition between a proton abstraction pathway leading to the trimethylsilyl-trapped organometallic species and a base-catalyzed, stereospecific 1,3 hydrogen shift.
- Benkeser, Robert A.,Snyder, Dudley C.
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p. 1243 - 1249
(2007/10/02)
-
- Mechanism of Diol Formation in the Reaction of Benzylic Grignard Reagents with Aldehydes
-
2-Hydroxymethyl-1-methylene-1,2-dihydronaphthalene (8) was obtained from the reaction of 1-naphthylmethylmagnesium chloride with monomeric formaldehyde.This compound slowly produces approximately equimolar amounts of 1-methylnaphthalene and 1-(2-hydroxyethyl)-2-hydroxymethylnaphthalene (9) in the presence of MgCl2.In the light of these results and studies on the reactivity of 1-naphthylmethylmagnesium chloride towards acetone and halide-free dibenzylmagnesium towards monomeric formaldehyde, a new mechanism of diol formation in the reaction of benzylmagnesium chloride with aldehydes is described.This mechanism involves an ortho addition on the Grignard reagent, leading to a trienic magnesium alkoxide intermediate (4), which decomposes by a reversible process into Grignard reagent and aldehyde.The latter undergoes a Prins-type reaction with the magnesium alkoxide intermediate in the presence of MgCl2, to give the corresponding diol and toluene.
- Bernardon, Claude,Deberly, Alain
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p. 2631 - 2636
(2007/10/02)
-
- Synthetic Photochemistry. XVIII. A Sensitizer Dependence in the Photooxidation of Indene and Acenaphthylene. The Occurrence of cis-1,2-Glycol Formation in a Rose Bengal-sensitized Reaction
-
Upon Rose Bengal-sensitized photooxygenation, indene and acenaphthylene afforded substantial amounts of the expected cis-glycols by means of the reduction of the intermediate dioxetanes.The formerly proposed structure of one of the isomeric methoxy hydroperoxides was revised on the basis of the chemical and spectral evidence.
- Hatsui, Toshihide,Takeshita, Hitoshi
-
p. 2655 - 2658
(2007/10/02)
-