Raghao S. Mali

A NEW ROUTE TO AMINOSUGARS FROM SUGAR NITRONES : SYNTHESIS OF 6-DEOXYNOJIRIMYCIN

Abstract The 1,3-addition of methylmagnesium chloride to dialdose derived nitrones 3 and 7 afforded N- benzylhydroxylamines 4 5 and 8 9 , respectively, in high yields. The stereoselectivity of the addition reaction was improved by the use of trimethylsilyl triflate. The NO bond reductive cleavages of N-benzylhydroxylamines took place in good yields and offered an easy access to N-benzylaminosugars. The potential of these aminosugars is demonstrated by the synthesis of glycosidase inhibitor 6-deoxynojirimycin 1a.

A short and efficient synthesis of enantiopure (+)-N-Boc-7-azabicyclo[2.2.1]heptan-2-one utilizing an asymmetric desymmetrization protocol: formal total synthesis of (−)-epibatidine

A short and efficient synthesis of optically pure (+)-N-Boc-azabicyclo[2.2.1]hept-2-one (2), a precursor in the synthesis of natural (−)-epibatidine (1), is reported by the asymmetric desymmetrization of meso-N-methoxycarbonyl-2,3-bis(phenylsulfonyl)-7-azabicyclo[2.2.1]hept-2-ene (3).

Convenient two-step syntheses of seselin and angelicin derivatives

Abstract Convenient two-step approaches are described for the syntheses of seselin ( 3a ), seselin and angelicin derivatives ( 3b–d and 5a–d ) from 2,4-dihydroxybenzaldehyde ( 1a ) and 2,4-dihydroxyacetophenone ( 1b ) using tandem Claisen rearrangement and Wittig reaction.

Convenient Synthesis of Dimethyl-1-Aryl-4-Hydroxy-N-Methylcarbazole-2,3-Dicarboxylates via Michael Initiated Ring Closure Methodology

Abstract A convenient method has been described for the synthesis of dimethyl-1-aryl-4-hydroxy-N-methylcarbazole-2,3-dicarboxylates ( 3a–d ) from ethyl N-methyl-2-benzylindole-3-carboxylates ( 2a–d ).

Novel AlCl3 catalysed syntheses of naturally occurring (±) 8-hydroxy-3-methyl-3,4-dihydroisocoumarins

Treatment of (±) 3-ethylphthalides 2 or 2-(prop-1-enyl)benzoic acids 5 with AlCl3 in methylene chloride gives naturally occuring (±) 8-hydroxy-3-methyl-3,4-dihydroisocoumarins 3 in high yields.

USEFUL SYNTHESES OF PRENYLATED- AND PYRANO-3-ARYLCOUMARINS

Convenient syntheses of 6-prenyl- and 8-isoprenyl-3-arylcoumarins (7a–d and 8c–d) from 2-prenyloxy-4-methoxybenzaldehydes (5a and 5b) and of pyrano-3-arylcoumarins (10a–b) from 2-hydroxy-4-(1,1-dimethylpropynyloxy) benzaldehyde (9) using Wittig reaction are described.

Efficient syntheses of 6-prenylcoumarins and linear pyranocoumarins: Total synthesis of suberosin, toddaculin, O-methylapigravin (O-methylbrosiperin), O-methylbalsamiferone, dihydroxanthyletin, xanthyletin and luvangetin

Synthesis of naturally occurring 6-prenylcoumarins (1a, 2c and 3a) and their derivatives 1c, 1d, 1e, 2d and 3b–d starting from 2-prenyloxybenzaldehydes (8, 12 and 14) using tandem Claisen rearrangement and Wittig reaction is described. The coumarins 1a, 1e and 2c are converted to dihydropyranocoumarins (5a–e). The conversion of dihydroxanthyletin 5a and dihydroluvangetin 5d to the naturally occurring linear pyranocoumarins xanthyletin 6a and luvangetin 6b is also described.

Useful synthesis of aryl cinnamates: synthesis of difengpin

A convenient, high yield and general method is described for the synthesis of difengpin (8a) and aryl cinnamates (8b–h and 9a,b) from benzaldehydes (7a–h).

Convenient Synthesis of 3-Styrylphthalides

Abstract A convenient, high yield, two-step method is described for 3-styrylphthalides (3a - e) from 3-phenacylphthalides (1a - e)

Expedient syntheses of naturally occurring (±)-3-benzylphthalides and (±)-3-aryl-8-hydroxy-3,4-dihydroisocoumarins: Structure revision of the (±)-3-benzylphthalide isolated from Frullania falciloba

A simple synthesis of (±)-3-benzyl-7-methoxyphthalides (1b, 1d and 4a–c) from 7-methoxyphthalides (3a–c) and a novel AlCl3-catalysed conversion of (±)-3-benzyl-7-methoxyphthalides (1d, 4a–c) to 4′-O-methylhydrangenol 5a, 4′,6-O,O-dimethylthunberginol-C 5b and related compounds (5c and 5d) is described.