Sulfur dioxide mediated syntheses of polyene containing natural products
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Even unsubstituted butadiene adds to sulfur dioxide in the hetero-Diels Alder mode more rapidly than in the chelotropic mode. The sultine can be observed in equilibrium with the diene and the sulfur dioxide only at low temperature and in the presence of CF ...
In the presence of a Lewis or protic acid and at low temperature, 1,3-dioxy-1,3-dienes add to sulfur dioxide generating zwitterionic intermediates that can react with carbon nucleophiles such as allylsilanes. After a retro-ene elimination of SO2, valuable ...
The energetics of dissocn. reactions of S82+ into stoichiometric mixts. of Sn+, n = 2-7, and Sm2+, m = 3, 4, 6, 10, were investigated by the B3PW91 method [6-311+G(3df)//6-311+G*] in the gas phase and in soln., with solvation energies calcd. using the SCIP ...
Under appropriate conditions sulfur dioxide reacts with 1,3-dienes in the hetero-Diels-Alder fashion. In the case of 1-alkoxy-1,3-dienes the 6-alkoxy-3,6-dihydro-1,2-oxatiin-2-oxides (sultines) so-obtained can be ionized in the presence of Lewis or protic ...
The ene reaction of sulfur dioxide with enoxysilanes or with allylsilanes generates silyl sulfinates that can be brominated (Br-2 or NBS) or chlorinated (NCS or Cl-2) to produce the corresponding sulfonyl halides. They react with primary and secondary amin ...
The preparation of [(2S,3S,4R)-3,4-dihydroxypyrrolidin-2-yl]furan derivatives in a stereoselective route starting from D-glucose and ethyl acetoacetate is presented. Ethyl ester (6), N,N-diethylamide (7) and N-isopropylamide (8) have been tested towards 25 ...
The present invention relates to a process for preparing sulfonyl halides comprising the steps of a) reacting an enoxymetal, allylsilane or allylstannane compound, preferably in the presence of a diene, with sulphur dioxide and b) adding a suitable halogen ...
The oxidation of organic and inorganic compounds during ozonation can occur via ozone or OH radicals or a combination thereof. The oxidation pathway is determined by the ratio of ozone and OH radical concentrations and the corresponding kinetics. A huge da ...
Ozonolysis of (1R,1'R,6R,6'R)-3,3'-methylenebis{6-[(benzyloxy)methoxy]cyclohept-3-en-1 -ol} followed by the diastereo-selective reduction of the resulting beta-hydroxy ketone intermediates gives a rapid route to long-chain polyketides bearing unsymmetrical ...
Chloroprene (= 2-chlorobuta-1,3-diene; 4b) and electron-rich dienes such as 2-methoxy-(4c), 2-acetoxy(dd), and 2-(phenylseleno)buta-1,3-diene (4e) refused to equilibrate with the corresponding sultines 5 or 6 between -80 and -10degrees in the presence of e ...
