Alkaline Degradation of 1,1-Disubstituted Sulfonhydrazides. Synthesis of a Pair of Cyclic, Benzylic Hydrazines Derived from Acenaphthene and Acenaphthylene¹

Potassium trimethylsilanolate induced cleavage of 1,3-oxazolidin-2- and 5-ones, and application to the synthesis of (R)-salmeterol

“…LCMS of the crude reaction mixture indicated the presence of small quantities of another diastereoisomer (4%). 25 The synthesis (Scheme 6) commenced by condensing the bromoketone 16 27 with di-tert-butyl iminodicarboxylate 17 28 in the presence of caesium carbonate in acetonitrile to give 18 in 53% yield. Even prolonged heating (24 h) with 5 equivalents of potassium trimethylsilanolate did not cleave the benzoyl group.…”

“…Previously we had used an excess of amino alcohol 13 for the direct alkylation to 15 in order to minimize the formation of dialkylated products, however, this is not efficient in terms of the expensive chiral reagent 13. 25 The synthesis (Scheme 6) commenced by condensing the bromoketone 16 27 with di-tert-butyl iminodicarboxylate 17 28 in the presence of caesium carbonate in acetonitrile to give 18 in 53% yield. One of the butoxycarbonyl groups was removed selectively using trifluoroacetic acid in dichloromethane (84%) and the resulting ketone 19 was reduced to the protected amino alcohol 20 using the chiral CBS-oxazaborolidine protocol 29 (99%) and in 98 : 2 diastereoisomeric ratio.…”

Synthesis of Two Complementary Molecular Moulds

“…[18] The two dimethylamide groups were then hydrolyzed, which after esterification, yielded dimethyl acenaphthene-4,5-dicarboxylate. [19] Monobromination with NBS and dehydrobromination with LiBr/DMF provided dimethylacenaphthylene-4,5-dicarboxylate. [19] This latter was finally hydrolyzed and dehydrated to give 8 as an orange powder (see Supporting Information).…”

“…[19] Monobromination with NBS and dehydrobromination with LiBr/DMF provided dimethylacenaphthylene-4,5-dicarboxylate. [19] This latter was finally hydrolyzed and dehydrated to give 8 as an orange powder (see Supporting Information). [20] Attempts were made to convert directly dicarboxylic anhydride 8 into its dicarboxylic imide derivative.…”

Synthesis and Study of Novel Coumarin Derivatives Potentially Utilizable as Memory Media

“…Reactions with moisture-sensitive chemicals were performed under argon in an oven-dried flask. N -Aminobenz[ de ]isoquinoline-1,3-dione ( 3b ) [ 15 ] and 2-oxo-2 H -chromene-3-carbaldehyde ( 1 ) [ 16 ] were prepared according to literature procedures. For column chromatography Merck silica gel 60, 230-400 mesh was used with the indicated eluents.…”