Synthesis of 2'-epi-distichonic acid A, an iron-chelating amino acid derivative.
作者:TAKASHI TASHIRO、SHINJI FUSHIYA、SHIGEO NOZOE
DOI:10.1248/cpb.36.893
日期:——
2'-epi-Distichonic acid A (4b), an iron-chelating amino acid derivative was synthesized starting from L-vinylglycine epoxide (6b). Reaction of 6b with glycine ester 17 afforded a β-hydroxy amino acid derivative (18). Reductive coupling of 21 derived from 18 with L-malic-β-semialdehyde (25) gave 2'-epi-distichonic acid A (4b) after deprotection.
Observations regarding eschenmoser sulfide contractions of β-oxygenated thiolactams
作者:David S. Hart、Li-Qiang Sun、Alan P. Kozikowski
DOI:10.1016/0040-4039(95)01648-2
日期:1995.10
Application of an Eschenmosersulfidecontraction to a thiolactam bearing a β-acyloxy group was complicated by a competitive β-elimination reaction. Changing the β-substituent to an alkoxy group retarded the rate of elimination such that sulfidecontraction products could be obtained.
Free radical cyclizations in alkaloid synthesis: (+)-heliotridine and (+)-hastanecine
作者:Joong-Kwon Choi、David J. Hart
DOI:10.1016/s0040-4020(01)97176-5
日期:1985.1
hydride and AIBN affords mixtures of reduction and cyclization products. Cyclization products partition between indolizidinones and pyrrolizidinones depending on the terminal alkyne substituent. When the terminal substituent is a trimethylsilyl group, synthetically useful yields of pyrrolizidinones are obtained. Applications of this chemistry to the synthesis of (+)-heliotridine (2) and (+)-hastanecine (3)
Two α-aminoxy diamides with fluorinated side chains were synthesized. Their secondary structures characterization was carried out by 1H NMR, and IR spectrometries as well as X-ray crystallography studies. α N–O turn secondary structures are adopted insusceptibly by side-chain-fluorinated α-aminoxy residues. Thus the fluorinated α-aminoxy diamide can be a potential residue as a biological tracer to
合成了两个带有氟侧链的α-氨基二酰胺。它们的二级结构表征是通过1 H NMR,IR光谱以及X射线晶体学研究进行的。侧链氟化的α-氨基氧基残基不易采用αN–O转向二级结构。因此,氟化的α-氨基二酰胺可以是潜在的残基,作为掺入氨氧基肽中的生物示踪剂。
Preferential hydrogenolysis of NAP esters provides a new orthogonal protecting group strategy for carboxylic acids
作者:Matthew J. Gaunt、Carlos E. Boschetti、Jinquan Yu、Jonathan B. Spencer
DOI:10.1016/s0040-4039(99)00014-3
日期:1999.2
Selective hydrogenolysis of 2-naphthylmethyl (NAP) esters in the presence of a benzyl ester has been observed with a wide range of dicarboxylic acids. Orthogonal deprotection of NAP esters with challenging substrates can be achieved if the other carboxylic acids in the molecule are protected with 4-trifluoromethyl benzyl group instead of benzyl groups.