Robert Lorne

Reductions of steroidal halohydrins and their esters by tri-n.butyltin hydride; some stereospecific 1.2-migrations of acetoxy- or benzoxy-groups

Abstract Six 5α-chloro- and one 5α-bromo-cholestane derivatives bearing hydroxy-, acetoxy- or benzoxy-groups in the 3β and 4β or 3β and 6β positions, 1 , 3 , 5 , 6 , 8 , 10 and 12 have been hydrogenolysed with the title reagent to afford the corresponding reduced derivatives. The reduction of 4α-chloro-5β-cholestane-3β, 5-diol 3-benzoate ( 14 ) and 3α-chloro-5α-cholestan-2β-ol acetate gave also the products of simple hydrogenolysis. However, four examples of a stereospecific 1.2-migration of an acetoxy-or benzoxy-group from a tertiary to a secondary carbon have been found during the hydrogenolysis of 6β-chloro-(or 6β-bromo)-5α-cholestane-3β,5-diol diacetates 18 , 19 , 4β-bromo-5α-cholestane-3β, 5-diol diacetate 22 and 4α-chloro-5β-cholestane-3β, 5-diol 5-monobenzoate 24 .

Diastereoselectivity in the [2,3]-sigmatropic rearrangement of substituted allylic N,N-dialkylamidosulfoxylates. X-ray molecular structure of [(1′) S*, (S)S*]-(2′E)-4-[[3′-(4″-bromophenyl)-1′-methyl-2′-propenyl]sulfinyl]-morpholine

Abstract By the reaction with three N,N-dialkylamidosulfenyl chlorides 2 bearing representative sizes for the R groups on the nitrogen atom, several substituted secondary E or Z allylic alcohols (1a-h) have been converted into the corresponding pairs of diastereoisomeric allylic sulfinamides (3+-3′a-v), whose ratios have been determined by 1H NMR spectroscopy. Five cases of entirely diastereoselective [2,3]-sigmatropic rearrangement have been observed. The stereochemistry of one pure diastereoisomer 3′m has been determined by single crystal X-Ray analysis. When treated with 4-morpholinesulfenyl chloride, cyclohex-2-en-1-ol is stereoselectively converted to one diastereoisomer of the sulfinamide 5b which, by unambiguous procedures, led to the sane p.tolylsulfoxide 5a already obtained by treatment of cyclohex-2-en-1-ol with toluene-p-sulfenyl chloride.

Unusual transformations of the chrysanthemic nitrile skeleton by sodium hydride in N,N-dimethylformamide

Abstract It is shown that the title transformations occurred through basecatalyzed opening of the cyclopropane ring into the dienic nitrile 4 which then reacted with the in situ formed formaldehyde to yield the bicyclic compound 5 .