Debabrata Mukherjee

Stereoselective total syntheses of (±)-1,14-herbertenediol and (±)-tochuinyl acetate and facile total syntheses of (±)-α-herbertenol, (±)-β-herbertenol and (±)-1,4-cuparenediol

Abstract Stereoselective total syntheses of (±)-1,14-herbertenediol ( 7 ) and (±)-tochuinyl acetate ( 10 ) and facile total syntheses of (±)-α-herbertenol ( 2 ), (±)-β-herbertenol ( 3 ) and (±)-1,4-cuparenediol ( 8 ) have been successfully accomplished involving intramolecular cyclisation of 3-aryl-3-methyl-6-bromohexanoates and in situ methylation of the resulting cyclopentanecarboxylates as the key reactions.

New total synthesis of (±)-herbertene, (±)-β-herbertenol and (±)-herbertenediol

Abstract The total syntheses of the herbertane sesquiterpenes (±)-herbertene ( 1 ), (±)-β-herbertenol ( 2 ) and (±)-herbertenediol ( 5 ) have been successfully accomplished involving copper-catalysed conjugate addition of Grignard reagents to unsaturated compounds and α,α-dimethylation of primary esters as key reactions.

Facile total synthesis of (±)-α-herbertenol, (±)-α-cuparenone and (±)-HM-1 methyl ether involving alkylation of hindered esters

Abstract The total syntheses of (±)-α-herbertenol 1 , (±)-α-cuparenone 4 and (±)-HM-1 methyl ether 3 have been successfully accomplished involving α,α-dimethylation of the esters 8a, 17 and 8b respectively as key steps.

A stereocontrolled total synthesis of (±)-zizaene

Abstract A stereocontrolled approach to the construction of the tricyclo[6.2.1.01,5]undecane ring system related to the sesquiterpene zizaene is delineated. Starting from an indanone, a bromophenol was prepared in a straightforward manner. An intramolecular anionic cyclisation then afforded a tricyclic dienone which was stereoselectively converted into a mesylate through various intermediates. Base induced rearrangement furnished a trans-fused ketone as the sole product which was converted into (±)-zizaene through Wittig olefination.

A total synthesis of (±)-herbertene

Abstract A total synthesis of (±)-herbertene (1) has been accomplished using the benz[e]indenone 3 as a key intermediate.

Stereoselective synthesis of cis-A/B octahydrophenanthrene skeleton related to diterpenes via reductive alkylation in anhydrous ammonia

Abstract 7-Methoxy-1,1,4aβ-trimethyl-1,2,3,4aβ,9,10,10aβ-octahydrophenanthrene ( 5 , a skeletal representative of several diterpenes, has been synthesised stereoselectively through reductive methylation of the ∝,β-unsaturated ketone 14 in anhydrous ammonia followed by Huang-Minlon reduction.

Studies on Intramolecular Cyclisations. Synthesis of Ring Systems Related to Sesquiterpene Noids

Abstract Intramolecular reactions of diazocarbonyl compounds have provided1 synthetic routes to many novel ring systems. For synthetic entry into the basic carbon skeleta of several tricyclic sesquiterpenoids, we have studied acid-catalysed intramolecular cyclisations of a few diazo-ketones derived from suitably substituted indanones and tetralones. The tricyclic dienediones 1 +, 2, 3 and 4 have been prepared in this way in 42%, 16%, 24% and 26% yields respectively from the acids 8, 13, 16, and 18. Although the yields are not high, the method is convenient since the starting materials are readily accessible and the pure dienediones are easily isolated from the crud products through chromatography on silica gel.

A stereocontrolled total synthesis of (±)-norzizanone

Abstract A stereocontrolled total synthesis of (±)-norzizanone 1 has been efficiently accomplished involving base-induced rearrangement of the mesylate 17 as the key step. Aryl participated intramolecular cyclisation of the bromophenol 11 provided the tricyclic dienone 12, which was stereoselectively converted into the mesylate 17.

Aryl participated cyclisations involving indane derivatives a total synthesis of (±)-isolongifolene

Abstract A total synthesis of (±)-isolongifolene (1) has been accomplished using intramolecular anionic cyclisation of the bromophenol 2 as the key step. Aryl participated intramolecular cyclisation of the diamethyl ketones 17 and 23 provided the dienediones 18 and 24 which were stereoselectively converted into the diketones 19 and 25 respectively.

Synthesis of 3,3-Dimethyl-5-methoxy-l-indanone and 9,9-Dimethyl-2-methoxy-5-benzosuberone

Abstract In connect ion with synthetic studies towards tricyclovetivene1 and hinschalene2 class of sesquiterpenes, w e required adequate quan-tities of 3,3-dimethyl-5-methoxy-1-indanone (1) and 9,9-dimethyl-2-methoxy-5-benzosuberone (2) as intermediates. The search of the literature revealed that a onestep Synthesis of the indanone 1 has been reported3 through Friedel-Crafts reaction of anisole with α, β-dhethylacryloyl chloride in the presence of anhydrous AlC13. The reported procedure, however, yielded ii our hands only the acrylo-phenone 3 in 72% yield, b.p. 133–132°C/1 mm; 1R (CHCI3) 1665 (s) and 1600 (s) cm−1; 1H-NMR (CC14) δ 7.85–6.7 (m, 4H), 6.5 (m, 1H), 3.77 (s, 3H), 2.15 (d, 3H, J = 1 Hz), 1.95 (d, 3H, J = 1 Hz). Similar observation has been reported recently by Kasturi et.al4. Although acid-catalysed cyclisation of several acrylophenones to indanones have been reported5, all our attempts to cyclise the acrylophenone 3 failed. In the present communication, we wish to report convenient Syntheses o...