S. Swaminathan

Asymmetric one-pot Robinson annulations

Abstract One-pot syntheses of ketol SS - 5a , enone S - 2 and optically active spiroenediones S - 14 , R - 7 and S - 15 are reported.

Base catalysed rearrangement of a spiro oxy-cope system and related studies: A new entry into perhydrophenalene and perhydroacenaphthylene systems☆

Abstract The spirovinyl carbinol 5 when treated with methanolic potassium hydroxide was found to rearrange to perhydrophenalene- 1,4-dione 6 via an anionic oxy-Cope rearrangement followed by an intramolecular Michael addition. The epimeric mixture of ketol acetates 15a and 15b was also found to rearrange to 2-hydroxy-2-methyl perhydroacenaphthylene-1,3-dione 16 on treatment with base.

A dianionic oxy-cope rearrangement route to benzotropones - Part XII.

The divinyl carbinols 3 and 6 furnished the benzotropones 4 and 7 respectively, when treated with base.

A transannular reaction in an anionic oxy-cope system9

Abstract The carbinol 8 is found to rearrange to the bicyclo (2,2,2) octane derivative 10 in the presence of base; the rearrangement involves a transannular reaction in a ten membered ring resulting from an Oxy-Cope system.

Base catalyzed rearrangement of oxy-cope systems

The synthesis and rearrangement of the optically active etynyl and vinyl carbinols 3 and 4 are reported. The rearrangements are found to be concerted when carried out with KH-THF and non-concerted with KOH-methanol.

Rearrangements of bicyclic-δ-hydroxy-α,β-enones—IV : Base catalysed rearrangements of some bicyclic-α-substituted-δ-hydroxy-α,β-enones

The hydroxy enones 5a, 5b, 5c, 4d, 4a and 4b rearrange when treated with aqueous alkali to the diones 6a, 6b, 8 and 13 and acids 9 and 12 respectively. The diones 2 and 6a are also formed by thermal rearrangement of enones 1a and 5a.

Synthesis of Δ7-1-methylbicyclo[5,4,0]undecene-2,9-dione and its condensation with acetylene

Abstract Michael addition of methylvinyl ketone to 2-methylcycloheptane-1,3-dione (II) obtained by methylation of cycloheptane-1,3-dione furnishes 2-methyl-2(3′-oxobutyl) cycloheptane-1,3-dione (III) which is cyclized and dehydrated in a single step to afford the title compound (Ic) in the presence of a mixture of pyrrolidine and acetic acid. A by-product isolated in this cyclization is the bridged ketol VII. Treatment of III with p -toluenesulphonic acid gives predominantly the acid IV and only low yields of Ic. The reaction of Ic with lithium acetylide furnishes an unexpected product formulated as IX. An explanation for the differing course of ethynylation of the analogous diones Ia, Ib and Ic is given.

A new synthesis of angularly substituted bicyclic systems via an anionic oxy-cope rearrangement

Abstract A general synthesis of trans bicyclic carbinols with an angular methyl substituent using the anionic oxy-Cope rearrangement is reported. The carbinols 13a , l3b , 14a , 14b and 15 furnish the bicyclic carbinols 16a , 16b 17a , 17b and 18 when treated with potassium hydride in 1,2-dimethoxyeth ane.

Base catalysed rearrangement of oxycope systems

The synthesis and rearrangements of the chiral carbinols 8 and 9 are described. With KH-THF. both the carbinola gave optically active rearrangement products; with alkali in methanol, they gave optically inactive rearrangement products. The results are interpreted as favouring a concerted mechanism for the hydride catalysed rearrangements and a non-concerted mechanism for the rearrangements catalysed by alkali in methanol.

A new synthesis of angulary substituted octalins via an anionic oxy-cope rearrangement

The divinyl carbinols 3a and 3b furnished octalinols 4a and 4b respectively on treatment with base.