822-35-5Relevant articles and documents
Microwave Spectroscopy of Isotopic Cyclobutene Ozonide as a Means of Quantification of Ozone Isotopomers
Larsen, Niels Wessel,Pedersen, Thorvald
, p. 372 - 382 (1994)
The microwave spectrum of cyclobutene ozonide, a new isotopomeric species, has been assigned and the absolute direction of the dipole moment has been determined. The aim of this investigation has been to determine symmetric/asymmetric isotopomer concentrations in an arbitrary 18O-substituted ozone isotopomer mixture. The method we have used consists of transforming the ozone into cyclobutene ozonide and using intensities of rotational lines of these to quantify the composition of the original ozone isotopomer mixture. Such a method has been accomplished; unfortunately propagation of errors renders it difficult to obtain results of high accuracy.
THE MICROWAVE SPECTRUM, STRUCTURE AND DIPOLE MOMENT OF CYCLOBUTENE OZONIDE (2,3,7-TRIOXABICYCLOHEPTANE)
Borseth, Donald G.,Lorencak, Primoz,Badawi, Hassan M.,Hillig II, Kurt W.,Kuczkowski, R. L.,Mendenhall, G. David
, p. 125 - 134 (1988)
cyclobutene ozonide containing deuterium, 13C and 18O enrichment was prepared by ozonolysis of cyclobutene and via singlet molecular oxygen addition to furan.It was established that the ozonide has Cs symmetry.The structure was determined from the assignment of the microwave spectra of eight isotopic species.The peroxy bond distance of 1.492(5) Angstroem is increased by about 0.03 Angstroem compared with less strained monocyclic ozonides.The ring strain is also evident in several other bond distances and angles when compared with cyclopentene ozonide.The dipole moment is 2.857(2) debye.
Fluoroalkyl-Containing 1,2-Disubstituted Cyclobutanes: Advanced Building Blocks for Medicinal Chemistry
Demchuk, Oleksandr P.,Hryshchuk, Oleksandr V.,Vashchenko, Bohdan V.,Trofymchuk, Serhii A.,Melnykov, Kostiantyn P.,Skreminskiy, Artem,Volochnyuk, Dmitriy M.,Grygorenko, Oleksandr O.
, p. 87 - 95 (2021)
Synthesis of previously unavailable 1,2-disubstituted cyclobutane building blocks bearing mono-, di- and trifluoromethyl groups are disclosed. The key steps included deoxofluorination or TMAF-mediated nucleophilic substitution in the appropriate bifunctional cyclobutanes; for the CF3-substituted derivatives, alternative methods based on cyano- or azidotrifluoromethylation of cyclobutene using the Togni reagent II were also proposed. All methods provided trans diastereomers of the target primary amines and carboxylic acids (6 representatives) and were suitable for their multigram preparation. Furthermore, dissociation constants (pKa) and lipophilicity (logP) values were measured to evaluate the effect of the fluoroalkyl substituents on acidity/basicity and lipophilicity of the building blocks obtained.
Lessons in Strain and Stability: Enantioselective Synthesis of (+)-[5]-Ladderanoic Acid
Hancock, Erin N.,Kuker, Erin L.,Tantillo, Dean J.,Brown, M. Kevin
supporting information, p. 436 - 441 (2019/11/25)
The synthesis of structurally complex and highly strained natural products provides unique challenges and unexpected opportunities for the development of new reactions and strategies. Herein, the synthesis of (+)-[5]-ladderanoic acid is reported. En route to the target, unusual and unexpected strain release driven transformations were uncovered. This occurrence required a drastic revision of the synthetic design that ultimately led to the development of a novel stepwise cyclobutane assembly by an allylboration/Zweifel olefination sequence.
The cyclopropylcarbinyl route to γ-silyl carbocations
Creary, Xavier
supporting information, p. 1769 - 1780 (2019/08/07)
The mesylate derivative of cis-1-hydroxymethyl-2-trimethylsilylcyclopropane has been prepared, along with a number of related mesylates and triflates with substituents on the 1-position. These substrates all solvolyze in CD3CO2D to give products derived from cyclopropylcarbinyl cations that undergo further rearrangement to give 3-trimethylsilylcyclobutyl cations. These 3-trimethylsilylcyclobutyl cations are stabilized by a long-range rear lobe interaction with the γ-trimethylsilyl group. When the substituent is electron-withdrawing (CF3, CN, or CO2CH3), significant amounts of bicyclobutane products are formed. The bicyclobutanes are a result of γ-trimethylsilyl elimination from the cationic intermediate that has an unusually long calculated Si-C bond. The solvolysis chemistry of mesylate and triflate derivatives of trans-1-hydroxymethyl-2-trimethylsilylcyclopropane and 1-substituted analogs can be quite different since these substrates do not generally lead to 3-trimethylsilylcyclobutyl cations.
A Diverted Aerobic Heck Reaction Enables Selective 1,3-Diene and 1,3,5-Triene Synthesis through C-C Bond Scission
McAlpine, Neil J.,Wang, Long,Carrow, Brad P.
supporting information, p. 13634 - 13639 (2018/10/24)
Substituted 1,3-dienes are valuable synthetic intermediates used in myriad catalytic transformations, yet modern catalytic methods for their preparation in a highly modular fashion using simple precursors are relatively few. We report here an aerobic boron Heck reaction with cyclobutene that forms exclusively linear 1-aryl-1,3-dienes using (hetero)arylboronic acids, or 1,3,5-trienes using alkenylboronic acids, rather than typical Heck products (i.e., substituted cyclobutenes). Experimental and computational mechanistic data support a pericyclic mechanism for C-C bond cleavage that enables the cycloalkene to circumvent established limitations associated with diene reagents in Heck-type reactions.
Formal (4+1) cycloaddition of methylenecyclopropanes with 7-aryl-1,3,5-cycloheptatrienes by triple gold(I) catalysis
Wang, Yahui,Muratore, Michael E.,Rong, Zhouting,Echavarren, Antonio M.
supporting information, p. 14022 - 14026 (2015/02/19)
7-Aryl-1,3,5-cycloheptatrienes react intermolecularly with methylenecyclopropanes in a triple gold(I)-catalyzed reaction to form cyclopentenes. The same formal (4+1) cycloaddition occurs with cyclobutenes. Other precursors of gold(I) carbenes can also be used as the C1 component of the cycloaddition.
Accuracy of calculations of heats of reduction/hydrogenation: Application to some small ring systems
Wiberg, Kenneth B.
, p. 10393 - 10398 (2013/01/15)
The enthalpies of reduction of carbonyl compounds and hydrogenation of alkenes have been calculated at the HF, B3LYP, M06, MP2, G3, G4, CBS-QB3, CBS-APNO, and W1BD levels and, in the case of the first four methods, using a variety of basis sets up to aug-cc-pVTZ. The results are compared with the available experimental data, and it is found that the compound methods are generally more satisfactory than the others. Large basis sets are usually needed in order to reproduce experiments. Some C-C bond hydrogenolysis reactions also have been examined including those of bicycloalkanes and propellanes. In addition, the dimerization of the remarkably strained bicyclo[2.2.0]hex(1,4)ene was studied. The reaction forming a pentacyclic propellane was calculated to have ΔH = -57 kcal/mol, and the cleavage of the propellane to give a diene had ΔH = -71 kcal/mol. The strain energies of these compounds were estimated.
γ-silyl cyclobutyl carbocations
Creary, Xavier,Kochly, Elizabeth D.
supporting information; experimental part, p. 9044 - 9053 (2010/03/04)
(Graph Presented) A series of 3-trimethylsilyl-1-substituted cyclobutyl trifluoroacetates have been prepared and reacted in CD3CO 2D. Rate data indicate that the substrates with the trimethylsilyl group cis to the leaving group react with assistance due to γ-silyl participation. Rate enhancements range from a factor of 209 for α-phenyl-substituted cations to 4.6 × 104 for α-methyl-substituted cations to >1010 for the unsubstituted γ-trimethylsilylcyclobutyl cation. Acetate substitution products are formed with net retention of stereochemistry. These experimental studies, as well as B3LYP/6-31G* computational studies, are consistent with the involvement of carbocations where the rear lobe of the γ-Si-C bond interacts strongly with the developing cationic center. Solvolytic rate studies, as well as computational studies, suggest that the secondary γ-trimethylsilylcyclobutyl cation is even more stable than the β-trimethylsilylcyclobutyl cation, i.e., the γ-silyl effect actually outweighs the potent β-silyl effect. Although computational studies suggest the existence of certain isomeric cations, where the front lobe of the Si-C bond interacts with the cationic center, solvolytic evidence for the involvement of these front lobe stabilized cations is less compelling.
Enantioselective synthesis of pentacycloanammoxic acid
Mascitti, Vincent,Corey
, p. 3118 - 3119 (2007/10/03)
A highly effective enantioselective synthesis of pentacycloanammoxic acid (1), an unusual naturally occurring fatty acid from Candidatus Brocadia anammoxidans, has been accomplished. The C20-structure of 1 was assembled with stereocontrol from four building blocks, cyclobutene, 2-cyclopentenone, the chiral silylcyclopentenone 6, and 7-bromoheptanoic acid. Both 1 and its enantiomer are now available in quantities that should facilitate future studies on the mode of biosynthesis which appears to be unprecedented. Copyright
