Iodo-L-alanine

AMte/T-butoxycarbonyl)-3-iodo-L-alanine benzyl ester (FW 405), 304 mg, 0.75 mmol... 

Quickly place /V-(fert-butoxycarbonyl)-3-iodo-L-alanine benzyl esterc in the flask, followed by zinc/copper couple (0.09 g) (see Protocol 1). 

V-(benzyloxycarbonyl)-3-iodo-L-alanine ferf-butyl ester3 (FW 405.23), 3.24 g, 8 mmol... 

W-(benzyloxycarbonyl)-3-iodo-L-alanine fert-butyl ester was prepared by the literature method. 8 6THF was dried by distillation from potassium benzophenone ketyl. 

V-(fert-butoxycarbonyl)-3-iodo-L-alanine methyl ester is available from Aldrich Chemical Company. 

L-Alanine, N-[(l,l-dimethylethoxy)carbonyl]-3-iodo-, methyl ester]... 

Phosphonium salt 482, which can also be prepared from alcohol 437 by treatment with methyltriphenoxyphosphonium iodide followed by triphenylphosphine, has been used in a stereoselective synthesis of 6-ep/-D-purpurosamine B (494) (Scheme 69) [122]. A Wittig reaction of the ylide generated from 482 and Cbz-L-alaninal (488) affords the Z-olefin 489. lodocyclization gives the trans-cyclocaihamatQ 490 in quantitative yield. Removal of the iodo group, hydrolysis of the acetonide, and benzoylation fhmishes 491. 

O2IOSC7HS, Osmium, dicarbonyI(Ti -cycIo-pentadienyI)iodo-, 25 191 02lOsC,2H,s, Osmium, dicarbonyliodo(Ti -pentamethylcyclopentadienyl)-, 25 191 O2NC2HS, Glycine cobalt complex, 25 135 02NC3Ht, Alanine cobalt complex, 25 137 02N4P2QH,2, 1 W,5W-[1, 4,2,3]Diazadiphos-phoIo[2,3-b][l,4,2,3]diazadiphosphoIe-2,6-(3W,7W)-dione, 1,3,5,7-tetrame-thyl-, 24 122... 

Thyroxine is derived from two molecules of di-iodo-phenol, and contains an alanine side-chain, thus being related to tyrosine, its precursor in the diet, and to iodogorgic acid. Owing to the asymmetric carbon atom in the side-chain, two forms of thyroxine are known, the natural hormone being the L (—)-isomer, derived from L-tyrosine. 

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