Lithium aluminum hydride promoted ring contraction of cyclic five-membered .alpha.-sulfonyl carbanions and its application to the synthesis of 1,2-dialkylcyclobutenes

1974 ◽  
Vol 96 (14) ◽  
pp. 4715-4717 ◽  
Author(s):  
James M. Photis ◽  
Leo A. Paquette
Keyword(s):  
Lithium Aluminum Hydride ◽  
Aluminum Hydride ◽  
Lithium Aluminum ◽  
Ring Contraction ◽  
Sulfonyl Carbanions

Stereochemical dependence of the mechanism of deoxygenation, with lithium triethylborohydride, in 4,6-O-benzylidenehexopyranoside p-toluenesulfonates

1985 ◽  
Vol 63 (11) ◽  
pp. 3043-3052 ◽  
Author(s):  
Hans H. Baer ◽  
Miroslawa Mekarska-Falicki
Keyword(s):  
Lithium Aluminum Hydride ◽  
Aluminum Hydride ◽  
Lithium Aluminum ◽  
Reduction Mechanism ◽  
Ring Contraction ◽  
Hydride Shift ◽  
Nucleophilic Displacement ◽  
Cleavage Reactions ◽  
Epoxide Formation

Lithium triethylborohydride was shown to react with methyl 4,6-O-benzylidene-α-D-hexopyranoside 2- and 3-tosylates, and 2,3-ditosylates, in the manno, allo, and altro configurational series both by O—S fission (O-desulfonylation) and by C—O fission (C-desulfonyloxylation), to produce carbinol and deoxy functions, respectively. The results were compared with those previously obtained with the corresponding gluco and galacto isomers, and the degree of facility of the cleavage reactions was seen to depend on the position of the sulfonic ester groups and the overall configuration of the molecules. The mechanism of reductive desulfonyloxylation also depended on configuration and was demonstrated to involve intermediary epoxide formation or displacement by internal hydride shift as the principal paths; competing elimination and direct nucleophilic displacement were found to occur in the allo series, whereas reduction accompanied by ring contraction has thus far been encountered only in the conformationally less constrained, cis-fused acetal system of the galacto series. Like the borohydride reagent, lithium aluminum hydride was found to react (though much more slowly) with the altro 2,3-ditosylate by the epoxide-mediated mechanism, although the latter hydride is known to desulfonyloxylate the α-D-gluco-isomer by a different, intramolecular reduction mechanism.

The Preparation of Specifically Deuterated trans- Cinnamyl Alcohol and trans- Cinnamic Acid

1973 ◽  
Vol 51 (13) ◽  
pp. 2102-2104 ◽  
Author(s):  
Donald G. Lee ◽  
James R. Brownridge
Keyword(s):  
Cinnamic Acid ◽  
Triple Bond ◽  
Lithium Aluminum Hydride ◽  
Aluminum Hydride ◽  
Lithium Aluminum ◽  
Cinnamyl Alcohol ◽  
Partial Reduction ◽  
Work Up

The reduction of ethyl phenylpropiolate by lithium aluminum hydride results in partial reduction of the triple bond to give trans-cinnamyl alcohol. If ethyl phenylpropiolate is reduced by LiAlD4 followed by work-up with acetone and H2O the product is the specifically labeled compound, trans-3-phenyl-2-propen-1-ol-1,1,2-d3. If the ester is reduced with LiAlH4 followed by work-up with acetone-d6 and D2O the product is trans-3-phenyl-2-propen-1-ol-O,3-d2. Oxidation of these two products by sodium ruthenate leads to formation of trans-cinnamic acid-α-d and trans-cinnamic acid-β-d, respectively.

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