The intramolecular, stereoselective addition of sulfoximine carbanions to electron deficient alkenes

Abstract only availableChiral Benzothiazine play important roles in synthetic organic chemistry since they can be used in the preparation of enantiomerically pure compounds. We have studied the synthesis of these species using the intramolecular, stereo selective addition of sulfoximine carbanions to general electron deficient alkenes. Details on the synthesis of starting material and cyclization reaction will be presented.Stevens' Chemistry Progra

Resolution and Determination of the Absolute Configuration of a Twisted Bis-Lactam Analogue of Troger's Base: A Comparative Spectroscopic and Computational Study

The first reported twisted bis-lactam, a racemic Tröger's base (TB) analogue (2), was resolved into its enantiomers on a chiral stationary phase HPLC column. The absolute configuration of (+)-2 was determined to be (R,R)-2 by comparing experimental and calculated vibrational circular dichroism (VCD) and electronic circular dichroism (ECD) spectra. The absolute configuration of (-)-2 was determined by comparing experimental and calculated electronic circular dichroism (ECD) spectra. The corresponding theoretical spectra were calculated using the lowest energy conformation of (R,R)-2 and (S,S)-2 at the B3LYP/6-31G(d,p) level of theory. The absolute configuration of (+)-2 was also determined to (R,R)-2 by anomalous X-ray diffraction (AXRD) in a chiral space group P212121 using Cu-irradiation resulting in a very low Flack parameter of -0.06(3), despite the heaviest element being an oxygen atom, thus unambiguously confirming the results from the spectroscopic studies. We conclude that, for the Tröger's base (TB) analogue (2), we may rank the reliability of the individual methods for AC determination as AXRD ≫ VCD > ECD, while the synergy of all three methods provides very strong confidence in the assigned ACs of (+)-(R,R)-2 and (-)-(S,S)-2

Strategies And Tactics in Organic Synthesis

xxiii;ill.;476hal.;22c

Carbanion Accelerated Claisen Rearrangements

239 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1985.A new variant of the Claisen rearrangement has been invented in which an arylsulfonyl-stabilized carbanion attached to carbon 2 of the allyl vinyl ether provides great acceleration to the 3,3 sigmatropic rearrangement. Two methods are reported for the synthesis of the appropriate allyl vinyl ethers, both involving the base catalyzed addition of allylic alcohols to arysulfonyl allenes. The rearrangement is shown to proceed through an arylsulfonyl-stabilized allylic anion. A study of methyl substitution at various positions on the allyl vinyl ether gave qualitative kinetic results in agreement with both the empirical and theoretical findings of others. The reaction is highly regioselective and stereoselective. Allyl vinyl ethers substituted at carbon 3 gave ketonic products containing only E double bonds. A proposal is formulated to explain certain regiochemical anomalies observed with allyl vinyl ethers substituted at carbon 3. Qualitative rate studies are reported which show little solvent and counterion effects in the rearrangement process. A rationalization for the rate changes observed in THF as a function of counterion is given. With allyl vinyl ethers substituted at carbons 1 and 5, the rearrangement was shown to proced via a chair transition state and with diastereoselection as good or better than its thermal counterpart. A study of several other carbanion stabilizing groups is reported. It was found that the arylsulfonyl group is the most efficacious stabilizing group for this reaction. Preliminary studies on the synthesis of allyl vinyl ethers containing arylsulfilimine or arylsulfoximine functions as carbanion stabilizing groups are also reported. Rearrangement of the sulfilimine based allyl vinyl ether substituted at carbon 5 resulted in no diastereoselection. A Friedel-Crafts reaction between a sulfoximidoyl chloride and an acetylene is also reported.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD