Janina Altman

Alkyne bridged α- amino acids by palladium mediated coupling of alkynes with N-t-Boc-4-iodo-phenylalanine methyl ester

Abstract The Heck reaction of trimethylsilylacetylene with N-t-Boc-4-iodo-L-phenylalanine methyl ester gives N-t-Boc-4-ethynyl-L-phenylalanine methyl ester (2). Coupling of 2 with different alkynes yields alkyne bridged linear amino acid esters 3– 5. Also tripodal and tetrapodal amino acid esters 10 and 11 were prepared by this approach. All compounds have been obtained in enantiomerically pure form. The protecting groups were removed by standard methods to yield the free amino acids as hydrochlorides.

A new synthesis of amino acids—II: Amidoalkylation of olefins with glyoxylic acid derivatives

Abstract A new synthesis of leucine, aspartie acid, aspartic acid semialdehyde and unsaturated N -acyl-α amino acid from olefins and glyoxylic acid-primary amide adducts is described. The chemistry and stereochemistry of the intermediate oxazines 7 and α-amidobutyrolactones 8 is also discussed

A new synthesis of α-amino acids—III: Amidoalkylation of active methylene compounds with glyoxylic acid derivatives

Abstract The synthesis of N-acyl derivatives of γ - keto - α - amino acids ( 3, 4, 5 ) by the amidoalkylation of 1,3-dicarbonyl compounds with glyoxylic acid-amide adducts ( 1, 2 ) is described. The γ - keto - α - amino acid derivatives ( 4, 5 ) were further converted to the corresponding butenolides ( 6, 7 ) and to pyrazolylglycine ( 12 ).

Propellanes—III : Synthesis of carbocyclic and heterocyclic compounds

Abstract Syntheses of carbocyclic, oxa-, aza-, and thiapropellanes, their physical properties and behaviour on electron impact are described.

Propellanes—I: Tricyclic compounds conjoined in a carbon—carbon single bond

Abstract The syntheses of a number of carbocyclic, oxa, and azapropellanes are described. Fragmentation paths of these compounds on electron impact are discussed as well as their NMR spectra and other physical properties.

Propellanes—IX : Carbocyclic and Heterocyclic compounds and organometallic derivatives of tetraenic propellanes☆

Abstract Propellane diketones and a propellane triketone have been prepared by multiple (intramolecular) Dieckmann condensations and a propellane tetraone by a Diels-Alder reaction. The synthesis of mixed oxa-thia and polyoxa and polythiat[3.3.3]propellanes is described. Bis -irontricarbonyl derivatives of tetraenic propallanes have been prepared.

The synthesis of p-substituted d,l-phenylglycines by the amidoalkylation of benzylchloride and N-benzylbenzamide

Abstract The synthesis of p -hydroxymethyl ( 3 ), p -bromomethyl ( 4 ), p -methoxy-methyl ( 5 ), p -methylthiomethyl ( 6 ) and p -aminomethyl-d, 1-phenylglycines by the amidoalkylation of benzylchloride and N-benzylbenzamide with α-hydroxyhippuric acid is described.

BENZENE-BRIDGED HEXAALKYNYLPHENYLALANINES AND FIRST-GENERATION DENDRIMERS THEREOF

The palladium-mediated coupling of p-ethynylphenylalanine (p-epa) with hexabromobenzene afforded the benzene-bridged hexaalkynyl α-amino acid 1 in high yield. Deprotection of 1 at the carboxylate terminus yielded the free hexa acid which was treated with amine H2NC(CH2OCH2CH2CO2CH3)3 to give a hexapodal first-generation dendrimer.

Amidoalkylation of aromatics with glyoxylic acid-γ-lactam adducts: 2-pyrrolidinone, pyroglutamic acid amide and ester

Abstract A glyoxylic acid-2-pyrrolidinone adduct leads to N-acyliminium-ion induced intermolecular electrophilic aromatic substitution yielding nitrogen-substituted phenylglycine derivatives, whereas the benzylamide of glyoxylic acid-2-pyrrolidinone adduct undergoes intramolecular amidoalkylation to give an isoquinolone type compound. High stereospecifity and enantioselectivity was observed in intermolecular amidoalkylation of benzene using glyoxylic acid-S-pyroglutamic acid ester or amide adducts.

The stereochemistry of 2,4-disubstituted γ-butyrolactones and 2,4,6-trisubstituted-5,6-dihydro-4H-1, 3-oxazines

2,4-Disubstituted butyrolactones and 2,4,6-trisubstituted-5,6 dihydro-4H-1,3-oxazines show similar features in their 1H and 13C- NMR spectra. Two geminal ring hydrogens of cis isomers give rise to a complex ABXY spectra when the substituent is alkyl or aryl. In spectra of trans isomers these patterns are degenerated. When R is OMe(in 4) or OCOMe (in 6) the difference in chemical shifts of geminal protons and vicinal coupling constants cannot be used for diagnosis. In 13C spectra ring carbons C-2 and C-3 in lactones and C-4 and C-5 in oxazine of trans isomers show a small but consistent shift to higher fields.