Kocienski rearrangement

A 1 2-metalate rearrangement of a higher order cuprate known as a Kocienski rearrangement [64] was used as a key step in the synthesis of the marine antiinflammatory sesterterpenoid manoalide 95 (Scheme 9.20) [65]. Treatment of the alkenyl lithium 89 (prepared from the alkenylstannane 88 with s-BuLi in a diethyl ether-pentane mixture) with the homocuprate 91 (produced from iodoalkane 90) gave the iodoalkene 94 in 72% overall yield from 88. The reaction proceeds as fol-... 

The reductive elimination of a variety of )3-substituted sulfones for the preparation of di-and tri-substituted olefins (e.g. 75 to 76) and the use of allyl sulfones as synthetic equivalents of the allyl dianion CH=CH—CHj , has prompted considerable interest in the [1,3]rearrangements of allylic sulfones ". Kocienski has thus reported that while epoxidation of allylic sulfone 74 with MCPBA in CH2CI2 at room temperature afforded the expected product 75, epoxidation in the presence of two equivalents of NaHCOj afforded the isomeric j ,y-epoxysulfone 77. Similar results were obtained with other a-mono- or di-substituted sulfones. On the other hand, the reaction of y-substituted allylic sulfones results in the isomerization of the double bond, only. The following addition-elimination free radical chain mechanism has been suggested (equations 45, 46). In a closely related and simultaneously published investigation, Whitham and coworkers reported the 1,3-rearrangement of a number of acyclic and cyclic allylic p-tolyl sulfones on treatment with either benzoyl peroxide in CCI4 under reflux or with... 

Plesniak K, Zarecki A, Wicha J (2007) The Smiles Rearrangement and the Julia-Kocienski Olefination Reaction. 275 163-250 Polito M, see Braga D (2005) 254 71-94 Poulin-Kerstien AT, see Dervan PB (2005) 253 1-31... 

The western part 97 of tylosin aglycon (96), a 16-membered macrolide, has also been synthesized using this Kocienski metalate rearrangement [66]. Treatment of the lithiated dihydrofuran 99 with the stannyl cuprate [67] obtained from Bu3SnLi and CuCN, followed by Mel alkylation, exclusively gave the E vinyl stan-nane 100, in 80% yield. In the last stage, stannyl cupration [68] of the deprotected enyne diol 101 afforded the desired ( , E) stannyl diene 97 in 85% yield. 

The Smiles Rearrangement and the Julia-Kocienski Olefination Reaction... 

Studies by Juba and by Kocienski have shown that the nature of the suhbne may exert a decisive effect on the efficiency of the olefination reaction. Diversification of the migrating rings in the Smiles rearrangement could be benefactions for extending the scope of appHcation of the reaction. 

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