Kinetic Resolution of Cyclic Sulfoxides by Enzyme Promoted Hydrolysis of 2-Alkoxycarbonyl-3,6-Dihydro-2H-Thiapyran-1-Oxides

Abstract

Among many methods of preparation of optically active sulfoxides, those applying enzymes are becoming more and more popular¹. In continuation of our recent investigations on the enzyme promoted hydrolysis of sulfinyldicarboxylates² we turned our attention to cyclic six-membered sulfoxides 1. These compounds are easily available by the cycloaddition reaction of butadienes with appropriate sulfines obtained in situ from the corresponding esters (or their O-silyl enolethers) with thionyl chloride in the presence of a base³. Three compounds shown in the scheme were chosen for our investigations. It should be noted that compounds lb and lc are obtained as single diastereoisomers.     

α-Oxo Sulfines and their Synthetic Behaviour

Abstract

Sulfines are reactive heterocumulenes which have been under investigation in our laboratory for a number of years¹. In this communication some new features of the chemistry of α-oxo sulfines are discussed.     

Study on Nucleophilic Additions to endo-tricyclo[5.2.1.0~(2,6)]deca-2(6),8-dien-3-one and an Unusual Payne Rearrangement of α,β-Epoxy Tricyclodecenone

The facial selectivity of nucelophilic additions to endo-tricyclo [5.2.1.02,6] deca-2(6),8-dien-3-one 1 demonstrates a high preference for exo-facial attack to the enone moiety1. We were interested in whether it would be possible to accomplish three-ring annulation to tricyclodecenone 1 by cyclopropanation or epoxidation. Three-ring annulation would lead to an increase in total ring strain as compared with the starting enone, not as previous nucleophilic addition reactions which release strain…     

Solution- and solid-phase synthesis of 4-hydroxy-4,5-dihydroisoxazole derivatives from enantiomerically pure N-tosyl-2,3-aziridine alcohols

[reaction: see text] Enantiomerically pure N-tosyl-2,3-aziridine alcohols are directly converted into 4-hydroxy-4,5-dihydroisoxazole 2-oxides through oxidation to the corresponding aldehydes followed by in situ tandem nitroaldol-intramolecular cyclization. This study was concerned with (i) the selection of a suitable aziridine activation, (ii) the preparation of the target 4-hydroxy-4,5-dihydroisoxazole derivatives in solution, and (iii) the elaboration of a solid-phase process using hydroxy Merrifield-supported nitroacetic acid ester.     

New resolving bases for ibuprofen and mandelic acid: qualification by binary phase diagrams

New resolving bases for ibuprofen 1 and mandelic acid 2 were studied and qualified by their binary phase diagrams of the corresponding salts. It was shown that analysis of the binary phase diagrams gives a good prediction for a resolution process. A comparison of resolving bases revealed that (S)-phenylglycinol (S)-7 is the best resolving base for ibuprofen 1. By the same procedure, various resolving bases for mandelic acid 2 were studied. The known resolving base (S)-MBA 9 was found to be the best for this acid.     

Ab initio and indo molecular orbital calculations of the geometries and electronic structures of substituted sulfines

Molecular orbital calculations are presented for the parent sulfine and some mono-and dihalogensubstituted sulfines, using ab initio and INDO methods. A partial geometry optimization was performed for nine different sulfines. Charge distributions, potential surfaces and dipole moments were calculated from the wave functions of the optimized geometries. Cis-trans interconversion barriers and electronic spectra are also given. The atomic charges of the S and O atoms are insensitive to substitutions at carbon, and substituents greatly influence the potential in the environment of the molecule. The implications of the results for the chemical behavior of sulfine derivates are briefly discussed and compared with experimental data.     

Crystal and molecular structure of 3,6-dihydro-4,5-dimethyl-2-[2-(methoxymethyl)pyrrolydinesulfonyl]-2-phenyl-2H-thiapyran-1-oxide,C19H27NO4S2

The crystal structure of a dihydrothiapyranS-oxide was determined from single-crystal diffractometer data, C₁₉H₂₇NO₄S₂, MoK radiation: orthorhombic, space groupP2₁2₁2₁, usinga=8.9604(10),b=13.5928(15),c=16.5621(19) Å,z=4. The molecule has theE-geometry, and the absolute configuration isR at C₁ andS at S₁.     

A new synthesis of p-hydroxy phenylglycine and some analogues from p-benzoquinone

[reaction: see text] A new route to p-hydroxy phenylglycine and N-substituted analogues has been developed starting from p-benzoquinone. 1,2-Addition of methyl lithioacetate to p-benzoquinone and subsequent quenching of the oxygen anion with methyl chloroformate, followed by an elimination-addition reaction with an appropriate amine, resulted in the desired amino acid derivatives. A diastereoselectivity of 60% was achieved using 8-phenylmenthyl acetate as the chiral auxiliary.