The dianions from a variety of P-keto esters have been generated using 1 equiv of sodium hydride and 1 equiv of n-butyllithium or methyllithium or 2 equiv of lithium diisopropylamide. The dianions react with a range of alkylating agents to produce y-alkylated products exclusively in good yield. Reaction of these dianions with a,wdihaloalkanes yields cyclic 1 : 1 adducts, cyclic 1 : 2 adducts, or acyclic 1 : 2 adducts, depending on the alkylating agent and the reaction conditions. This method offers ready access to a wide range of compounds which were previously difficult to obtain, ecently we had envisioned the synthesis of a num-(4) J. D. Hagarty, U. S. Patent 3,565,928 (1971); Chem. Absrr., 74, ( 5 ) T. M. Harris and C.

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FUK-WAH SUM and LARRY WEILER. Can. J. Chem. 57,1431 (1979). The anions from P-keto esters or P-diketones were reacted with diethyl phosphorochloridate to yield the corresponding en01 phosphates. These en01 phosphates were coupled with dialkylcuprates to produce the P-substituted a,P-unsaturated esters or ketones in good yield. Starting from acyclic P-keto esters this sequence was used to stereoselectively generate tri-and tetrasubstituted olefins.FUK-WAH SUM et LARRY WEILER. Can. J. Chem. 57,1431 (1979). On a fait rkagir les anions de P-cktoesters ou de P-dicktones avec le phosphorochloridate de dikthyle et Yon a obtenu les phosphates knoliques correspondants. On a effectuk une rkaction de copulation de ces phosphates knoliques avec des cuprates de dialkyles pour conduire, avec de bons rendements, aux cktones ou aux esters a#-non saturks substituks en P. En appliquant cette skrie de rkactions t~ des esters P-cktoniques acycliques, on a obtenu stkrkosklectivement des olefines tri-et tktrasubstituks.[Traduit par le journal]In the past decade there has been wide interest in developing new methods to synthesize tri-and tetrasubstituted alkenes in a stereoselective fashion (1). These alkenes have been very useful in the synthesis of a range of natural products, including insect pheromones and terpenes. Recently, we have been investigating methods to utilize P-keto esters in the synthesis of these types of natural products. Dianions of P-keto esters can be trapped by a variety of electrophiles at the y-carbon (2). These methods have been useful in the synthesis of acetogenins in which the P-keto ester moiety is directly incorporated into the final product (for some examples see ref.3). On the other hand, conversion of the ketone of a P-keto ester into a methylated olefin as shown in [I] would then constitute a method to incorporate an isoprene unit in a synthetic scheme. The utility of this transformation would be further enhanced if any alkyl group could be used in place of the methyl group in [I].Casey and co-workers (4) have reported that acyclic P-keto esters can be stereoselectively converted into either the (E) or (2) en01 acetates which then undergo a stereospecific reaction with lithium dimethylcuprate. These reactions were applied in a synthesis of geraniol (4a) and (52)-7-methyl-3-propyl-2,6-decadien-1-01 (5). This sequence involves treating acyclic P-keto esters with isopropenyl acetate and p-toluenesulfonic acid at high temperature to obtain the (2) en01 acetates (4, 5). Unfortunately these strong acid conditions severely limit the functionality which may be incorporated in R of [I]; indeed this sequence has only been successful when R is a hydrocarbon. Recently, we have prepared the en01 acetates of several cyclic P-keto esters and we find that they do not couple with dialkylcuprates. At low temperatures en01 acetate is recovered, and at higher temperature or after prolonged reaction times the acetate is cleaved to yield a mixture of cyclic P-keto ester and en01 acetate. House and co-workers (6) have sho...

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