Cyclopropylcarbinyl-oxo-carbonium Ions. Part VI. Synthesis and Chemistry of an Epimeric Pair of Homoallyl Iodides (3-Iodomethyl Glycals)

1972 ◽  
Vol 50 (18) ◽  
pp. 2919-2927 ◽  
Author(s):  
Bert Fraser-Reid ◽  
Bruno Radatus
Keyword(s):  
Transition State ◽  
Major Product ◽  
Alternative Route ◽  
Allylic Rearrangement ◽  
Reaction Products ◽  
Primary Reaction ◽  
Methylene Iodide ◽  
Carbonium Ions ◽  
Synthetic Sequence ◽  
Zinc Iodide

The homoallyl iodide 4,6-O-benzylidene-1,2,3-trideoxy-D-ribo-hex-1-enopyranose, 4, is the second major product from Simmons–Smith reaction of methyl 4,6-O-benzylidene-2,3-dideoxy-α-D-erythro-hex-2-enopy-ranoside, 6α. The major product is the cyclopropyl glycoside 7α, which when treated separately with the Simmons–Smith reagents furnishes an 85% yield of 4. The mechanism of this transformation is investigated. It is not simply a Lewis-catalyzed iodinolysis since zinc iodide in a variety of solvents does not convert 7α to 4. Methylene iodide is essential, as is the organo-zincate complex, operative in Simmons–Smith reactions.The 3-epimer of the homoallyl iodide 4, i.e. 4,6-O-benzylidene-1,2,3-trideoxy-D-arbino-hex-1-enopyranose, 5, is produced in only 0.9% yield in the methylenation of the anomeric olefinic glycoside, 6β. The low yield is attributable to the extensive anomerization experienced by 6β itself, and by the primary reaction products. This leads to a plethora of compounds including both epimeric homoallyl iodides 4 and 5.In order to get it all together, the homoallyl iodide 4 is transformed into its epimer 5 by an unambiguous synthetic sequence. Some of the intermediates in this sequence are polyfunctional molecules of considerable synthetic potential.The possibility of an alternative route to compound 4 directly from the olefinic glycoside 6α is discussed. Coordination of the methoxyl oxygen of 6α to the organo-zincate complex could achieve an ideal SNi transition state in which [Formula: see text] is delivered at C-3 with synchronous departure of the methoxyl group. This mechanism, called the "reverse" allylic rearrangement for reasons outlined in the text, is discussed.

scholarly journals Tuning the Reaction Selectivity over MgAl Spinel-Supported Pt Catalyst in Furfuryl Alcohol Conversion to Pentanediols

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 415
Author(s):  
Xinsheng Li ◽  
Jifeng Pang ◽  
Jingcai Zhang ◽  
Xianquan Li ◽  
Yu Jiang ◽  
...  
Keyword(s):  
Furfuryl Alcohol ◽  
Pt Nanoparticles ◽  
Catalytic Performance ◽  
Major Product ◽  
Pt Catalyst ◽  
Reaction Products ◽  
Strong Base ◽  
Reaction Selectivity ◽  
Supported Pt Catalysts ◽  
Alcohol Conversion

Catalytic conversion of biomass-derived feedstock to high-value chemicals is of remarkable significance for alleviating dependence on fossil energy resources. MgAl spinel-supported Pt catalysts were prepared and used in furfuryl alcohol conversion. The approaches to tune the reaction selectivity toward pentanediols (PeDs) were investigated and the catalytic performance was correlated to the catalysts’ physicochemical properties based on comprehensive characterizations. It was found that 1–8 wt% Pt was highly dispersed on the MgAl2O4 support as nanoparticles with small sizes of 1–3 nm. The reaction selectivity did not show dependence on the size of Pt nanoparticles. Introducing LiOH onto the support effectively steered the reaction products toward the PeDs at the expense of tetrahydrofurfuryl alcohol (THFA) selectivity. Meanwhile, the major product in PeDs was shifted from 1,5-PeD to 1,2-PeD. The reasons for the PeDs selectivity enhancement were attributed to the generation of a large number of medium-strong base sites on the Li-modified Pt catalyst. The reaction temperature is another effective factor to tune the reaction selectivity. At 230 °C, PeDs selectivity was enhanced to 77.4% with a 1,2-PeD to 1,5-PeD ratio of 3.7 over 4Pt/10Li/MgAl2O4. The Pt/Li/MgAl2O4 catalyst was robust to be reused five times without deactivation.

The mechanism of the pinacol-pinacone rearrangement. V. Carbon isotope effects

1957 ◽  
Vol 10 (1) ◽  
pp. 7 ◽  
Author(s):  
JF Duncan ◽  
KR Lynn
Keyword(s):  
High Temperature ◽  
Transition State ◽  
Carbon Isotope ◽  
Isotope Effects ◽  
Alternative Mechanism ◽  
Alternative Route ◽  
Temperature Reaction ◽  
Exchange Reactions ◽  
Carbonium Ion ◽  
High Temperature Reaction

The intermolecular isotope effects of methyl-labelled and alcoholic carbon-labelled pinacol converted to pinacone have been studied over a temperature range of 60-113.5 �C. Tests were made to establish the validity of the results by using two starting materials for synthesizing methyl-labelled pinacol, and several different methods of analysing the products. The isotope effects were determined by measurements made both on (i) pinacol and (ii) pinacone. The results above 80 �C can be interpreted in terms of the synartetic ion mechanism provided both the carbonium ion and the transition state are largely unhydrated, and both the formation of the carbonium ion and the methyl migration are slow steps. Below 60 �C an alternative mechanism is operative. Unless unsuspected exchange reactions are present, the results suggest that the transition state is not so greatly distorted from a simple ethane-type configuration as in the high temperature reaction. Results at intermediate temperatures indicate that the alternative route proceeds via a stable intermediate.

Reaction Products of Methylene Iodide with Tertiary Arsines

2005 ◽  
Vol 75 (2) ◽  
pp. 240-243
Author(s):  
R. D. Gigauri ◽  
L. G. Arabuli ◽  
Z. N. Machaidze ◽  
M. Sh. Rusiya
Keyword(s):  
Reaction Products ◽  
Methylene Iodide ◽  
Tertiary Arsines

The gaseous oxidation of 2-methyl-but-2-ene. I. Kinetic and analytical studies

1961 ◽  
Vol 262 (1310) ◽  
pp. 318-327 ◽  
Keyword(s):  
Double Bond ◽  
Methyl Alcohol ◽  
Initial Pressure ◽  
Pressure Increase ◽  
Reaction Products ◽  
Initial Attack ◽  
Primary Reaction ◽  
Slow Combustion ◽  
Propyl Ketone ◽  
Parallel Fashion

In the slow combustion of 2-methyl-but-2-ene at ca . 250 °C, an initial pressure decrease, which represents the formation of peroxidic intermediates, is followed by an autocatalytic pressure increase during which little olefin is consumed and the main processes are break ­ down and further oxidation of primary reaction products. Acetone and acetaldehyde are the principal early non-peroxidic products and these are formed initially in equivalent quantities and in closely parallel fashion. Methyl iso propyl ketone is produced in somewhat smaller amounts and methyl alcohol, which appears comparatively late in the reaction, probably arises from the oxidation of acetaldehyde. The results suggest that the predominant mode of initial attack of the olefin is addition of oxygen to the double bond followed by decomposition of the resulting cyclic peroxides, although some hydroperoxylation also occurs.

Dimethyl sulfoxide as a solvent in the Williamson ether synthesis

1969 ◽  
Vol 47 (11) ◽  
pp. 2015-2019 ◽  
Author(s):  
Russel G. Smith ◽  
Alan Vanterpool ◽  
H. Jean Kulak
Keyword(s):  
Reaction Time ◽  
Dimethyl Sulfoxide ◽  
Butyl Alcohol ◽  
Major Product ◽  
Hydroxyl Groups ◽  
Reaction Products ◽  
Butyl Chloride ◽  
Butyl Ether ◽  
Ether Synthesis ◽  
Williamson Ether Synthesis

Using the conventional Williamson ether synthesis, n-butyl ether was prepared from sodium hydroxide, n-butyl alcohol, and n-butyl chloride using excess of the alcohol as solvent in 61% yield after 14 h reaction time. However, when the excess alcohol was replaced by dimethyl sulfoxide, the yield of ether rose to 95% with 9.5 h reaction time. Other primary alkyl chlorides exhibited similar behavior to n-butyl chloride, but secondary alkyl chlorides and primary alkyl bromides gave little etherification, elimination being the major reaction. Unreactive halides, such as vinyl chloride, phenyl bromide, and 2,4-dinitrobromobenzene, were not etherified in dimethyl sulfoxide. The reaction products obtained from aliphatic dichlorides depended upon the relative positions of the chlorine atoms. Secondary alcohols reacted to give ethers, but tertiary alcohols were very unreactive. Polyols generally gave high yields of ethers, the major product being that in which all but one of the hydroxyl groups became etherified. Under forcing conditions, however, completely etherified polyols could be obtained.

Rubber. XVIII. Various Ozonides of Rubber and the Problem of the Existence of the Primary Ozonides of Harries

1938 ◽  
Vol 11 (1) ◽  
pp. 7-31
Author(s):  
Rudolf Pummerer ◽  
Hermann Richtzenhain
Keyword(s):  
Carbon Chain ◽  
Mesityl Oxide ◽  
Addition Reactions ◽  
Reaction Products ◽  
Primary Reaction ◽  
Carbon Chains ◽  
Fundamental Objection ◽  
Great Stress ◽  
Valuable Service ◽  
General Method

Abstract A permanently valuable service was rendered by Harries when he introduced the ozone cleavage of unsaturated compounds as a general method of investigation in organic chemistry. By analogy with other addition reactions of double bonded carbon atoms he derived the formula (a) for the ozonides which are first formed, but to support the existence of which he was able to obtain only scant experimental data. Harries relied above all on two observations, first, that mesityl oxide ozonide reverts to mesityl oxide when heated by itself, and, secondly, that fumaric acid is supposed to combine loosely with ozone and then readily split off again. Both of these suppositions have remained undisputed up to the present time. Harries reported that it was not possible, with any of a wide variety of reducing agents, to reduce the ozonides to the original compounds or to 1,2-glycols, as would be expected from their structure. Staudinger has laid great stress on this fundamental objection, and he considers that most ozonides have an isoözinide formula, as shown by formula (b) above, in which the carbon chain is already ruptured, so that by reduction only the usual types of cleavage products rather than glycols with intact carbon chains can be formed, as has been found experimentally. Staudinger assumed that the primary reaction products of treatment with ozone are molozonides containing the group:

Reaction products of diorganotin(IV) oxides, R2SnO, with nitric acid. Part 2 – R = n-butyl and t-butyl

2014 ◽  
Vol 92 (6) ◽  
pp. 484-495 ◽  
Author(s):  
Hans Reuter ◽  
Martin Reichelt
Keyword(s):  
Nitric Acid ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
Primary Reaction ◽  
Dimeric Molecule ◽  
X Ray ◽  
Trigonal Bipyramidal ◽  
Solvent Molecules ◽  
Hydroxide Hydrate ◽  
Hydrogen Bonded

The reaction of diorganotin(IV) oxides, R2SnO with R = n-butyl and t-butyl, with nitric acid in different stoichiometric ratios resulted in the formation of different products depending on the organic groups attached to the tin atom: the diorganotin(IV) dinitrate dihydrates, n-Bu2Sn(NO3)2·2H2O (2d) and t-Bu2Sn(NO3)2·2H2O (2e), the mixed diorganotin(IV) nitrate methoxide oxide n-Bu2Sn(NO3)(n-Bu2SnOMe)O (6), and the diorganotin(IV) nitrate hydroxide hydrate t-Bu2Sn(NO3)(OH)·H2O = [t-Bu2Sn(OH)(H2O)][NO3] (7). On examination of the solubility of the primary reaction products in different solvents, the three additional compounds t-Bu2Sn(NO3)(OH)·DMSO (8), t-Bu2Sn(NO3)(OH)·THF, and 2-t-Bu2Sn(NO3)(OH)·DMF = [t-Bu2Sn(OH)dmf]2[NO3]2·[t-Bu2Sn(NO3)OH]2 (9) could be isolated. All compounds have been structurally characterized by single crystal X-ray diffraction (primary results for 7) with special attention paid to dimensionality (2d and 2c = monomeric, hydrogen bonded molecules; 6 = dimeric molecules of ladder-type structure; 7 = dimeric cation; 8 = dimeric molecule with hydrogen bonded solvent molecules; 9 = both components dimeric), tin coordination (6, 7, 8, and 9 = trigonal bipyramidal; 2d and 2e = eightfold), and nitrate bonding modes (7 and 9 = isolated, hydrogen bonded; 6, 8, and 9 (component 2) = monodentate; 2d and 2e = symmetrical bidentate), the latter one being analyzed using both Sn–O and N–O distances.

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