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Sultones synthesis

Lewis Acid Assisted Nucleophilic Addition of Ketenes (or Sulfenes) to Aldehydes -Lactone and (i-Sultone Synthesis... [Pg.86]

Cava and Schlessinger have reported the synthesis of 1,2,3-triphenyl-isoindole (65) in 78% yield from 1,3-diphenylisobenzofuran (68) hy reaction with thionylaniline (69) and boron trifluoride. The mechanism proposed for this remarkable transformation involves reaiTangement of the adduct (70) derived from thionylaniline and the isobenzofuran, to the tricyclic intermediate (71). This presumably collapses to the S-sultam (72), which yields the isoindole (65) upon extrusion of sulfur dioxide. Loss of sulfur dioxide, both from S-sultones and unsaturated S-sultams, is well documented. ... [Pg.130]

The identity in sign and similarity in optical rotations of sultones (+)-52A,B, obtained from (—)-49A and (+)-49B, indicate that the absolute configuration of the y-carbon in both sultones as well as in both sultines is the same. In conclusion, the authors suggested113,114 that of the four possibilities shown below, y-sultines 48A-51A and 48B-51B may be assigned the (R)c-(Sf and (R)c-(Rf absolute configurations, respectively. Although initiated by mechanistic interest, this study has also resulted in a new method for selective synthesis of... [Pg.684]

Synthesis and Diels-Alder reactions of a,/f-unsaturated y-sultone [151]... [Pg.88]

Another total synthesis of pamamycin-607 (lb) was reported in 2001 by our own group [6] at about the same time as the Lee synthesis. Here, the approach was based on the stereoselective intramolecular Diels-Alder reaction of vinyl-sulfonates and novel methods for elaboration of the resulting sultones [13,14]. [Pg.222]

Much research has been done on the synthesis of perhalogenated P-sultones. The sulfonation of acyclic fluorovinyl ethers leads to a product that is stable up to slightly above room temperature. Thermolysis decomposes the ring structure under SO2 evolution and formation of acid fluorides and perfluorocyclopropane (Eq. 78). )S-Sultones have been synthesized by addition of sulfonyl chlorides to perhalogenated ketones in the presence of triethylamine. The formation of the l-oxa-2-thiacyclobutane 2,2-dioxides appears to require an activated but sterically unhindered carbonyl group because acetone, chloroacetone, trifluoroacetophenone, and p-nitroaceto-phenone did not yield the desired products. ... [Pg.273]

A six-step synthesis of nonactic acid with excellent stereocontrol via sultone intermediates has been published (Scheme 26) <1998EJO2073>. The tricyclic sultone 107 was synthesized by a tandem esterification/cycloaddition with vinylsulfonyl chloride whereby only the fvo-adduct with fvo-Me was obtained <1989AGE202>. Next, the tandem elimination/alkoxide-directed 1,6-addition first led to a mixture of sulfones, but equilibration with catalytic... [Pg.699]

A sultone analog of 107 (4-Me(eq)) instead of 3-Me(eq))] is the key intermediate of the first enantioselective total synthesis of the antileukemic l,10-ji ( ti-eudesmanolides, (—)-eriolanin and (—)-eriolangin <2001EJ03669, 2006EJ01144>. [Pg.700]

Reaction sequences for the synthesis of a number of exotic sultones 186-188 have also been proposed and the compounds synthesized subsequently in high yields (Scheme 52) <1990AP987, 1984H(22)2293>. [Pg.720]

Oxathin 2,2-dioxides (5-sultones) were used in the synthesis of menthofuran (152). Pulegone (329) and isopulegone (330) were converted into 5-sultones with a cold mixture of acetic anhydride and concentrated sulfuric acid (Scheme 87) (66AHC(7)377). Pyrolysis of (328) under basic conditions causes elimination of the sulfur dioxide. This method of preparation has been used for the synthesis of di-, tri- and tetra-alkylfurans. [Pg.692]

Alkene synthesis. Some years ago Julia and Paris1 reported an alkene synthesis hy reaelion of/i-alkoxy sultones with sodium amalgam (equation I). [Pg.579]

While the previous version of this chapter contained small sections on the synthesis of fluorinated and nonfluorinated /3-sultones along with /3-sultines and 1,2-oxathietanes, there has been no major new advances on the synthesis of these types of systems over the last decade. It appears that until practical industrial or medicinal uses are found, new methodologies for the constmction of such systems will not be developed. [Pg.806]

Further examples of RCM in heteronine synthesis include a variety of 1,2,7-thiadiazonines 261, which can be incorporated into a peptide sequence <2004JOC3662>, and unsaturated nine-membered sultone 262 <2004S1696, 2002SL2019>. [Pg.593]

Under microwave irradiation, carbazole reacted remarkably fast with a number of alkyl halides to give Af-alkyl derivatives of carbazole (82) (Bogdal et al., 1997). The reaction was carried out with high yields by simply mixing carbazole with an alkyl halide, which was adsorbed on potassium carbonate. A facile synthesis of a series of A-alkylpyrrolidino fullerenes (83) by phase transfer catalysis without solvent under microwave irradiation has been described by De la Cruz et al. (1998), while Adamczyk and Rege (1998) have illustrated the dramatic rate acceleration for A-sulfopropylation of heterocyclic compounds using 1,3-propane sultone under microwave irradiation affording the A-sulfopropylated compounds in 68-95% yield. [Pg.192]

The /J-sultone formed in the reaction of sulfur trioxide with tetrafluoroethenc itself is a key intermediate in the synthesis of Nafion polymers, which have commercial use as ion-exchange membranes. Furthermore, perfluorovinylsulfonyl fluoride (3) is transformed into mainly the /Tsultone 4 when heated with sulfur trioxide at elevated temperature. ... [Pg.626]

Synthesis o/eslra-l,3,5(10)-(rieiie-17-oii . Nicolaou and Barnette report that sultone 1 is metalated with KH in DME to afford a clear yellow solution of the anion 2. Alkylation of 2 with tosylate 3 followed by acid hydrolysis affords 4 as a mixture of diastereomers in 77% yield. Thermolysis of 4 affords estra-1,3,5(10)-triene-17-one (5) directly in 85% yield, probably by way of an intermediate o-quinone methide a. This sequence constitutes an exceedingly short and efficient synthesis of the steroid nucleus. [Pg.89]

A different approach to the asymmetric Diels-Alder reaction involves the use of the sultam derived from CSA. Lewis acid-promoted reaction with dienes followed by reductive removal of the chiral auxiliary is analogous to that previously discussed for the sultone. Smith has successfully utilized this approach to synthesize the chiral acid used in the synthesis of the immunosuppressant FK-506 (eq 16). ... [Pg.174]


See other pages where Sultones synthesis is mentioned: [Pg.323]    [Pg.63]    [Pg.323]    [Pg.63]    [Pg.757]    [Pg.848]    [Pg.255]    [Pg.212]    [Pg.50]    [Pg.223]    [Pg.225]    [Pg.238]    [Pg.200]    [Pg.272]    [Pg.464]    [Pg.679]    [Pg.700]    [Pg.718]    [Pg.31]    [Pg.31]    [Pg.32]    [Pg.757]    [Pg.848]    [Pg.86]    [Pg.268]    [Pg.279]    [Pg.6]    [Pg.781]    [Pg.757]    [Pg.848]    [Pg.513]   
See also in sourсe #XX -- [ Pg.764 ]

See also in sourсe #XX -- [ Pg.367 , Pg.369 , Pg.372 , Pg.373 , Pg.755 ]




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