175690-17-2

Upstream product

• 28143-91-1 (1S,2S)-2-amino-1-phenyl-1,3-diol 
• 407-25-0 trifluoroacetic anhydride 
• 383-63-1 ethyl trifluoroacetate, 

Downstream Products

• 175690-18-3 N-[(1S,2S)-1-(tert-Butoxy-diphenyl-silanyloxymethyl)-2-hydroxy-2-phenyl-ethyl]-2,2,2-trifluoro-acetamide 
• 175690-19-4 N-[(1S,2S)-1-(tert-Butoxy-diphenyl-silanyloxymethyl)-2-(tert-butyl-dimethyl-silanyloxy)-2-phenyl-ethyl]-2,2,2-trifluoro-acetamide 
• 175690-20-7 (1S,2S)-1-tert-butyldimethylsilyloxy-1-phenyl-2-trifluoroacetamidopropan-3-ol 
• 169137-66-0 (2S,3S)-2-amino-3-((tert-butyldimethylsilyl)oxy)-3-phenylpropan-1-ol 
• 159299-39-5 (4S,1''S)-4-(1''-tert-butyldimethylsilyloxy-1''-phenyl)-methyl-3-<(E)-4'-ethoxy-2'-oxo-3'-butenoyl>-oxazolidin-2-one 
• 159299-37-3 (4S,1'S)-(1'-tert-butyldimethylsilyloxy-1'-phenyl)-methyloxazolidin-2-one 
• 180262-30-0 N-{(1S,2S)-1-[Bis-(4-methoxy-phenyl)-phenyl-methoxymethyl]-2-hydroxy-2-phenyl-ethyl}-2,2,2-trifluoro-acetamide 

Relevant academic research and scientific papers

Synthesis and properties of combinatorial libraries of phosphoramidates

We have assembled a set of combinatorial libraries of phosphoramidates for pharmacological evaluation. A range of functionalized and unfunctionalized diols, representing a variety of diversity elements, were converted into their corresponding dimethoxytrityl H-phosphonate derivatives which were coupled to each other to produce H-phosphonate dimers and trimers. The H-phosphonate diesters were converted into phosphoramidates by reaction with a wide range of primary and secondary amines. Very large libraries (theoretically, in excess of one million compounds) possessing five sites of diversity were generated for use in our drug discovery program. Smaller libraries with lower molecular weights were also prepared in which only two monomeric units were coupled together and converted into their phosphoramidate derivatives. Methods for the attachment of both radioactive and nonradioactive labels, including 32phosphorus, tritium, and fluorescein, have been developed. Representative single sequences were also prepared and their chemical properties studied.

Stereodivergent Hetero-Diels-Alder Reactions of Chiral 1-Oxa-1,3-butadienes through a Conformational Switch induced by Lewis Acids

The stereodivergent asymmetric hetero-Diels-Alder reaction of achiral and chiral 1-oxa-1,3-butadienes carrying an oxazolidine moiety with various enol ethers in the presence of different Lewis acids is described as a highly stereoselective and efficient approach to dihydropyrans, which can be used for the synthesis of carbohydrates.In the cycloaddition of the achiral oxabutadiene very good endo/exo selectivity was possible, and with the chiral oxabutadienes excellent 1,6-asymmetric induction was additionally observed.In the processes a reversal of facial selectivity occurs by changing the Lewis acid, allowing the synthesis of both enantiomers of the dihydropyrans with the same auxiliary.Thus, cycloaddition of 1 to 2 in the presence of Me2AlCl gives predominatly the endo product 3 (3:4)=10:1), whereas with SnCl4 the exo product 4 is obtained (3:4=1:15).The reaction of 7 and 1a in thepresence of Me2AlCl as promoter nearly exclusively yields the endo-I adduct 16a (16a+17a:18a+19a=>50:1; 16a:17a=60:1), whereas with TMS-OTf the endo-II-product 17a was obtained as the main component (16a+17a:18a+19a=>50:1; 16a:17a=1:7.9).The use of SnCl4 leads to a mixture of endo and exo, again, however, with excellent induced selectivity.A similarly good induction was obtained with the oxabutadiene 9 containing the new auxiliary 8.Also, other enol ethers 1b-g were used, some of which afforded excellent induction.Mechanistic considerations are used to explin the results. - Keywords: asymmetric syntheses; Diels-Alder reactions; dihydropyrans; Lewis acids; oxabutadienes