2-tert.-Butyl-4-hydroxymethyl-5-methyl

Bis-[trifluormcthyl]-tert.-butyl- E2, 167 Bis-[2,4,6-trimethyl-phenyl]- XII/1, 194 Bis-ftrimethylsilyloxy]- XII/2, 116 El,. 339,424 aus phospltoriger Saure und Chor-trimethyl-silan/Triethylamin El, 340f. Bis-[4-trimethylsilyl-phenyl]-phenyl- E2, 37 Brommethyl-hydroxymethyl-methyl- E2, 53 (l-Brommethyl-vinyl)-dicthyl- E2, 13 (4-Brom-phenyl)-hydroxy- El, 128 (3-Brom-propyl)-(cthoxycarbonyl-methyl)-phenyl-E2, 24... 

Cyclopropan l-(tert.-Butyl-dimethyl-silyl)-l-hydroxymethyl-2-methyl-E17b, 1768 (COOR - CH2-OH)... 

Bromo-2-hydroxymethyl-3-methyl-3-(4-methyl-2-oxo-pentyl)- 1182 5-Bromo-3-methoxy- 1870, 1932 5-Bromo-3-oxo- 1179, 1742 5-Bromo-3-trichloromethyl- 1184 5-Bromo-3-trifluoromethansulfonyloxy-1179,1737 3-(tert.-Butylaminocarbonyloxy)- 1873 5-[3-(tert.-Butyl-dimethyl-silyloxy)-l-octenyl]-3-methoxy- 1873, 1874... 

In respect of proteciwi esters, we prepared both tert-butyl and 2-phenylpnopyl-2 (PP) esters. Though PP esters are deprotected acidolytically faster than its tert-butyl counterpart and seems to be convenient for the present purpose, the PP tosylate (2b and 2d) was rather thermally labile so that it does not fulfill the present requirements. Finally, we employed tert-butyl acetoacetate having a tosyloxymethyl substituent at an a-carbon (2a) as the add amplifier for the present purpose. This compound of mp 52-53 °C was synthesized by the a-methylation of tert-butyl acetate, followed by a-hydroxymethylation with formalin and tosylation in a 10% overall yield (2). 

---