O-tert-butyldimethylsilyl

The reaction of O-methyl-O-tert-butyldimethylsilyl ketene acetal with N-benzyl- and A-methyl-2,3-O-Mopropylidene D-glyceraldehyde nitrones (292), in the presence of boron trifluoride etherate, affords the corresponding isoxazolidine-5-ones in high yields. These compounds were successfully applied as key intermediates in the synthesis of isoxazolidinyl nucleosides of the L-series (Scheme 2.177) (638). 

Nevertheless, the direct nucleophilic displacement of support-bound carboxylates to prepare hydroxamates presents some limitations. For example, O-tert-butyldimethylsilyl-protected hydroxylamine displaces common acids from oxime resin however, further treatment with trifluoroacetic acid (TFA) is necessary to remove completely the silyl... 

The isocyanide method of reduction has been applied successfully for preparing a series of diversely protected 1,4-anhydroalditols 188 l,4-anhydro-5-O-tert-butyldimethylsilyl-2,3-0-isopropylidene-D-ribitol (56, 81%), l,4-anhydro-5-0-terf-butyldimethylsilyl-6-deoxy-2,3-0-isopropylidene-D-allitol (57,87%) and -l-talitol (58,87%), 1,4-anhydro-2- 0-rert-butyldimethylsilyl-3,5- 0 -isopropylidene-... 

Table 16 O-Trimethylsilyl-, 0-[2-(Trimethylsilyl)ethyl]-, and O-tert-Butyldimethylsilyl-Protected Tyrosine...

Oxazolidine 144 obtained from amino alcohol 143 and ethyl trifluoropyruvate is also a synthetic intermediate for 2-amino-2-trifluoromethylpentanoic acid 145. Lewis acid-catalyzed allylation of 144 with allyl silane occurs in excellent yield with a moderate stereoselectivity. Meanwhile, O-tert-butyldimethylsilyl-protected imine 146 gives better diastereoselectivity although yield is poor (see Scheme 9.31) [57]. 

Fiigedi, P (1989). Synthesis of heptakis (6-O-tert-butyldimethylsilyl) cyclomalto-heptaose and octakis (6-O-tert-butyldimethylsilyl) cyclomaltooctaose. Carbohydrate Research, 193, 366. 

Towards this end, iodoamidation reactions were carried out on a variety of protected glucals tri-O-acetyl-D-glucal, tri-0-ben q l-D-glucal and tris-O-tert-butyldimethylsilyl-D-glucal (Scheme 1, 1) with several primary alkyl and aryl amides (32). The addition reactions of substituted ureas and protected amino acids were also investigated. 

Procedure. Equip a roimd bottomed flask with a magnetic stirrer bar and a rubber septum and flush this with argon, then flame dry it and allow it to cool, while maintaining the inert atmosphere. To the reaction vessel add phenyl 2,3,4-tri-O-benzyl-6-O-tert-butyldimethylsilyl-1 -seleno-a-D-mannopyranoside (83 mg,... 

Z -1 -Deoxy-1 -(dibenzyloxyphosphoryl)fluoromethylidene-2,3,5,6-tetra-O-tert-butyldimethylsilyl-D-galactofuranose [(2)-2] and [1(1 ) E]-l-Deoxy-l-(dibenzyloxyphosphoryl)fluoromethylidene-2,3,5,6-tetra-0-... 

Oxirans. - Glycal derivatives have been treated with dimethyl-dioxirane affording 1,2-anhydro-sugars with the stereo-chemistry determined by the orientation of the substituent at C-3. 3,4,6-Tri-O-tert-butyldimethylsilyl-D-glucal afforded the 1,2-anhydride (20) as the only product, and 4,6-0-benzylidene-3-0-tert-... 

O -tert-butyldimethylsilyl-2 -deoxy-adenosine the C-nucleosides 1,3-dlmethyl-8-3-D-ribofuranosyl-xanthine monohydrate and 5-C-(2-amino-2-deoxy-3-D-glucopyranosyl)barbituric acld, and the carbocyclic 2 -deoxyurldine analogue (20). ... 

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