Sheetal Handa

Synthesis of chiral β-amino sulfides and β-amino thiols from α-amino acids

Abstract Bifurcated routes to two series of chiral secondary s-amino sulfides 5a - c and 11a - c have been developed from L-proline and ( S )-phenylglycine, respectively. The developed methodology has also led to the synthesis of the tertiary s-amino thiol 7 and the primary s-amino sulfide 12 from L-proline and ( S )-phenylglycine, respectively.

An expedient synthesis of (R)-(+)-umbelactone

The synthesis of the naturally occurring 2(5H)-furanone (R)-(+)-umbelactone 1 in five steps and 26.2% overall yield from (2S)-2,3-dihydroxy-(2,3-O-isopropylidene)propanoic acid 2 is described

Scalemic beta-amino sulfide ligands: use in enantioselective conjugate additions and x-ray analysis of a dimeric copper(I) complex

The enantioselective conjugate addition using a number of scalemic β-amino sulfide ligands to achieve enantiomeric excesses of up to 64% are described together with the X-ray absolute structure analysis of a dimeric copper(I) complex.

Synthesis of β-1-homonojirimycin and β-1-homomannojirimycin using the enzyme aldolase

The four stereoisomers of the four-carbon azido sugar 11 have been stereoselectively synthesised by a route involving Sharpless epoxidation and all are found to be substrates for rabbit muscle fructose 1,6-bisphosphate aldolase, giving (after treatment with phosphatase) 6-azido-6-deoxyheptuloses 14; hydrogenation of 14a and 14b gave β-1-homomannojirimycin 15a and β-1-homonojirimycin 15b with high selectivity.

Biosynthesis of vitamin B12: when is the 12β-methyl group of the vitamin generated by acetate decarboxylation?

The 12-methyl analogue (13) of the aromatised form of precorrin-3(5) has been prepared by enzymic C-methylation of 12-decarboxy-urogen-III (2) and is used for incorporation experiments which indicate that decarboxylation of the 12-acetate residue in B12-biosynthesis occurs after C-17 methylation.

The enantioselective synthesis of an important intermediate to the antiviral, (–)-carbovir

Two new routes to the important intermediate (–)-8 for the carbocyclic-based nucleosides are reported. The intermediate (–)-8 has also been synthesised in high. Enantiomeric excess via an enzymatic resolution of the racemic amide (+)-8 or an enzymatic enantiotopic hydrolysis of the meso diester 12.

A Route to Homochiral (S)-O-Methyl Mandelic Acid and Related α-Alkoxy Carboxylic Acids from Isopropylidene Glycerol

Abstract An improved synthesis of the useful ketones 7 is described. These ketones are then further modified via a highly stereospecific reduction. to give homochiral α-alkoxy carboxylic acids which are useful chiral auxiliaries and intermediates.

A short, stereospecific synthesis of a morphine fragment via an intramolecular Diels–Alder reaction

Intramolecular Diels–Alder reaction of trienes (8) gives the octahydroisoquinolones (10) which are readily converted into the biologically-active (12), a substructure of morphine.

Synthetic studies on morphine-based analgesics. Intramolecular Diels–Alder approach to 4a-aryldecahydroisoquinolines

An efficient, stereospecific synthesis of the trans-4a-aryldecahydroisoquinoline skeleton, a substructure of morphine known to possess analgesic activity, is described.

A novel approach to the 5a-aryldecahydro-2-benzazepine skeleton

Abstract Trienes ( 3 ) are prepared and their intramolecular cyclisation to give the 5a-aryloctahydrobenzazepines ( 6 ) is described.