Synthesis of 4′-amino-4′-deoxy analog of pantothenic acid

The synthesis of $\text{D}$- and $\text{L}$-N-(4-amino-3, 3-dimethyl-2-hydroxybutyryl)- β-alanine ($\text{7}$) is described. Compound $\text{7}$ is an analog of pantothenic acid in which the 4′-hyroxy group is replaced by amino group. The synthetic sequence leading to $\text{7}$ involved the synthesis $\text{D}$L-4-amino-3,3-dimethyl-2-hydroxybutyric acid and its resolution. Coupling of N-benzyloxycarbonyl N-hydroxysuccinimide ester ($\text{5}$) with β-alanine and followed by removal of the protecting group gave $\text{7}$.     

Synthesis of “9-deazaadenosine”; A new cytotoxic C-nucleoside isostere of adenosine

The synthesis of 7-(β-$\text{D}$-ribofuranosyl)-4-amino-5H-pyrrolo[3,2-$\text{d}$]pyrimidine (9-deazaadenosine) $\text{9}$ is described. It involves base-catalyzed cyclization of N-carboethoxyenamine $\text{4}$ to give β- and α-ribosylated 3-amino-2-cyanopyrroles $\text{6}$ and $\text{7}$, respectively, followed by a one-step conversion to the desired pyrrolo[3,2-$\text{d}$]pyrimidine system.     

Synthesis of oxazolidin-2-ones using carbonate ion on a polymeric support

Through the insertion of a carbon dioxide molecule, the oxazolidin-2-ones ($\text{5a}$) and ($\text{5b}$) were prepared by treataent of the salts ($\text{4a}$) and ($\text{4b}$) with carbonate anion on polymeric support. The hydrolysis under basic conditions of ($\text{5a}$) and ($\text{5b}$) afforded the erythro-3-amino-1,2-diols ($\text{6a}$) and ($\text{6b}$) which were fully acetylated: the 2-amino-2-deoxyerythritol derivative ($\text{7b}$) was obtained in 91% yield.     

An improved synthesis of the antiviral acyclonucleoside 9-(4-hydroxy-3-hydroxymethylbut-1-yl)guanine

Alkylation of 2-amino-6-chloropurine with 5-(2-bromoethyl)-2,2-dimethyl-1,3-dioxan ($\text{7}$) and subsequent acid hydrolysis provides an improved procedure for synthesis of the antiviral acyclonucleoside 9-(4-hydroxy-3-hydroxymethylbut-1-yl) guanine ($\text{3}$).     

Synthetic studies on β-lactam antibiotics. 19. Synthesis of 3′-nor-type 1-oxacephems

Synthesis of optically active 3′-nor-type 1-oxacephems from 6-APA was described. $\text{p}$-Nitrobenzyl 7β-amino-3-chloro-7α-methoxy-1-oxa-3-cephem-4-carboxylate $\text{39}$ was also prepared.     

The resolution of racemic 2-alkyl-1-aminocyclopropane-1-carboxylic acids

Practical procedures for the resolution of racemic modification of (1$\text{R}$, 2$\text{S}$)-and (1$\text{S}$, 2$\text{R}$)-1-amino-2-ethylcyclopropane-1-carboxylic acid $\text{1a}$,$\text{b}$,(1$\text{R}$, 2$\text{S}$)- and (1$\text{S}$, 2$\text{R}$)-1-amino-2-methylcyclopropane-1-carboxylic acid $\text{2a}$,$\text{b}$, and (1$\text{R}$, 2$\text{R}$)- and (1$\text{S}$, 2$\text{S}$)-1-amino-2-methylcyclopropane-1-carboxylic acid $\text{3a}$,$\text{b}$ are described; the structures as $\text{1a}$,$\text{2a}$, and $\text{3a}$ were confirmed by X-ray-crystallographic methods.     

Shikimate-derived metabolites. 10. Synthetic studies on the biosynthesis of para-aminobenzoic acid.

The total synthesis of $\text{trans}$-4-amino-3-hydroxycyclohexa-1,5-diene carboxylic acid $\text{7}$, an hypothetical intermediate in the biosynthesis of $\text{p}$-aminobenzoic acid, has been achieved.     

Regiospecific introduction of a branched-chain to kanamycin B and stereospecific transformation of the 2,6-diamino-2,6-dideoxy-D-glucopyranosyl moiety into 2,6-diamino-2,3,4,6-tetradeoxy-3-C-methyl-l-arabino or lyxo-hexopyranosyl,or 2-amino-2,3,4,6-tetradeoxy-5-C-methyl-L-threo-hexopyranosyl

4-O-(2,6-diamino-2,3,4,6-tetradeoxy-3-C-methyl-β-L-arabino and lyxo-hexopyranosyl) and 4-O-(2-amino2,3,4,6-tetradeoxy-5-c-methyl-L-threo-hexopyranosyl-6-O-(3-amino-3-decxy-α-D-glucopyranosyl)-2-deoxystreptamine ($\text{6}$, $\text{7}$ and $\text{12}$) were synthesized from a kanamycin B derivative ($\text{1}$) by regiospecific methylation and stereospecific hydrogenation followed by removal of masking groups, converting a D-sugar moiety (4-O-glycoside portion) into L-sugar. The usual conformation of $\text{6}$ and $\text{7}$ were determined as boat and skew by 250 MHz PMR spectra respectively.     

Acyclic stereocontrolled synthesis of (−)-detoxinine

Allylic oxidation of (2S)-N-$\text{t}$-butoxycarbonyl-2-amino-4-pentenoic acid methyl ester afforded, stereoselectively, a (2S,3R)-2-amino-3-hydroxyl derivative, which was converted to the unusual amino acid (?)-detoxinine $\text{via}$ a chelation controlled aldol condensation followed by a pyrrolidine ring formation.     

Bioactive marine metabolites IX. Mycalisines A and B,novel nucleosides which inhibit cell division of fertilized starfish eggs,from the marine sponge mycale sp.

Two novel nucleosides, mycalisines A and B, have been isolated from a marine sponge and their structures elucidated as 4-amino-5-cyano-7-(3-$\text{O}$-methyl-5-deoxy-β-D-$\text{erythro}$-pent-4-enofuranosyl)-pyrrolo[2,3-$\text{d}$]pyrimidine and 5-cyano-7-(3-$\text{O}$-methyl-5-deoxy-β-D-$\text{erythro}$-pent-4-enofuranosyl)-pyrrolo[2,3-$\text{d}$]pyrimidine-4-one, respectively. Both compounds inhibit cell division of fertilized starfish eggs.     

Synthesis applications of aza-cope rearrangements. Stereoselective synthesis of trans-alkyl-cis-3a-aryloctahydroindolones.

The reaction of both $\text{cis}$- and $\text{trans}$-2-amino-1-(1-phenylvinyl)- cyclopentanols with aldehydes affords $\text{trans}$-2-alkyl-$\text{cis}$-3a-aryl-4-oxo-octahydro indoles stereoselectively.     

Formal synthesis of (±)-perhydrohistrionicotoxin

The syntheses of 1-benzyl-7-butyl-1-azaspirocyclo[5.5]undec-7-ene (14) [a formal precursor of perhydrohistrionicotoxin (2)] and the thermodynamically preferred, exocyclic isomer (13) in six steps from the readily available $\text{N}$-benzyloxycarbonyl-10-amino-Δ^1,9-octalin (5) are reported.     

Amino acids derivatives that stabilize secondary structures of polypeptides-- : I. Synthesis of LL-3-amino-2-piperidone-6-carboxylic acid (LL-Acp), a novel beta-turn-forming amino acid

A six-step synthesis is reported of $\text{LL}$-3-amino-2-piperidone-6-carboxylic acid from $\text{L}$-homoserine lactone and the $\text{mono}$-$\text{t}$-butyl ester on $\text{N}$-benzyloxycarbonylaminomalonic acid. Evidence of chiral integrity is discussed.     

Reaction of 2-arylazo-2, 5-dimethyl-3(2H)-furanones with ammonia. Preparation of β-acetyl-β-(3-amino-2-butenoyl) arylhydrazines.

Ring opening of 2-arylazo-2,5-dimethyl-3(2H)-furanones ($\text{1a–d}$) with ammonia leads to previously unknown β-acetyl-β-(3-amino-2-butenoyl)arylhydrazines ($\text{3a–d}$). The reaction mechanism is discussed.     

The synthesis of γ-fluoroisoleucine

Condensation of 3-fluoro-2-butanone ($\text{2}$) with alkyl diethylphosphonoacetates ($\text{4a–d}$) gave alkyl 4-fluoro-3-methyl-2-pentenoates ($\text{5a–d}$). Addition of bromine yielded alkyl-2,3-dibromo-4-fluoro-3-methylpentanoates ($\text{6a,b}$) which were dehydrobrominated to alkyl 2-bromo-4-fluoro-3-methyl-2- pentenoates ($\text{7a,b}$). Since these compounds could not be hydrogenated to the desired alkyl 2-bromo-4-fluoro-3-methylpentanoates ($\text{8a,b}$), another route was taken. The esters $\text{5a–d}$ were hydrogenated to alkyl 4-fluoro-3- methylpentanoates ($\text{11a–c}$) which were converted to their carbanions. Treatment with bromine gave esters $\text{8a–c}$, and iodine gave alkyl 4-fluoro-2-iodo- 3-methylpentanoates ($\text{12a,b}$). Esters $\text{8a–c}$ and $\text{12a,b}$ were converted to alkyl 2-azido-4-fluoro-3-methylpentanoates ($\text{13a–c}$) whose hydrogenation gave alkyl 2-amino-4-fluoro-3-methylpentanoates ($\text{14a–c}$). Hydrolysis afforded γ-fluoroisoleucine ($\text{1}$).     

Nachbargruppenbeteiligungen bei der substitution von 2-amino-2-desoxy-α-d-glucopyranosiden in der 3-stellung

Neighboring group participation severely restricted nucleophilic substitution of N-protected 2-amino-2-deoxy-3-O-mesyl-α-D-glucopyranosides with azide ion. N-acetyl as blocking group led to the formation of the oxazoline $\text{3}$ while from N-dinitrophenylderivatives epimers were formed via the aziridine $\text{11}$.     

Preparation of fused meso-ionic compounds from 1-amino-4,6-diphenyl-2-pyridone

A number of meso-ionic compounds derivatives of the bicyclic system 1,3,4-oxadiazolo[3,2-a]pyridine have been prepared from 1-amino-4,6-diphenyl-2-pyridone, either by thermal way or $\text{via}$ iminophosphorane ($\text{4}$)     

Synthesis applications of aza-cope rearrangements.: Stereocontrolled synthesis of cyclohepta [b]pyroolidines1

Both $\text{cis}$- and $\text{trans}$-3a-aryl-4-oxo-decahydrocyclohepta[b]pyrroles can be prepared in stereocontrolled fashions by the reaction of 2-amino-1-(1-phenyl- vinyl)cyclohexanols with formaldehyde and acid.     

(-)-β-Pinene as chiral promoter. Stereospecific access to (-)-γ-amino-β(r)-hydroxybutyric acid (gabob) and (r)-carnitine.2

The stereochemical correlation between the ene adducts 2 and 4a and their products of alkaline hydrolysis is reported. Starting from 2, by using a degradative sequence, a stereocontrolled approach to γ-amino-β($\text{R}$)-hydroxybutyric acid (GABOB) 8f and ($\text{R}$)-carnitine hydrochloride 8g is described.     

New developments in the synthesis of lower fluorinated pyridines via diazotization-fluorination of aminopyridines in anhydrous hydrogen fluoride

The isolation and stabilization of elusive 4-fluoropyridine as the hydrochloride salt (54% yield) from fluorodediazoniation of 4-aminopyridine in anhydrous hydrogen fluoride (AHF) is described. Unlike the low yields (0–13%) recently reported from the chlorodediazoniation of 2,6-diaminopyridine and 3-halo-2,6-diaminopyridine, fluorodediazoniation gave high yields (49–62%) of the corresponding 2,6-difluoropyridines. In contrast, benzene analogs, i.e. $\text{m}$-phenylenediamine and 4-chloro-$\text{m}$-phenylenediamine, form only tars under similar fluorination conditions. Vicinal aminohalopyridines, e.g. 3-amino-2-chloropyridine and 2-amino-3,5-dichloropyridine give the corresponding fluorohalopyridine in 49–89% yield. Again, the benzene analogs, i.e. $\text{o}$-chloroaniline and 2,4-dichloroaniline, resist fluorination.