Drury Caine

Alkylations of Enols and Enolates

The α-alkylation of carbonyl compounds by their conversion into nucleophilic enolates or enolate equivalents and subsequent reaction with electrophilic alkylating agents provides one of the main avenues for regio- and stereo-selective formation of carbon–carbon σ-bonds.1–6 Classical approaches to α-alkylation typically involve the deprotonation of compounds containing doubly activated methylene or methine groups and having pKa values of 13 or below by sodium or potassium alkoxides in protic solvents. Since these conditions lead to monoenolates derived from deprotonation only at the α-site of the substrate, the question of the regioselectivity of C-alkylation does not arise (however, there is competition between C- and O-alkylation in certain cases). In more recent years, dienolates of β-dicarbonyl compounds have been utilized in γ-alkylations with excellent success.

A new synthesis of the california red scale pheromone from s-(+)-carvone

Abstract A Retroaldol-Wittig olefination of the s-(+)-carvone derivative 3 is used as a key step in the synthesis of pheromone 1.

A new route for the conversion of carvone into eudesmane sesquiterpenes

Abstract The β-hydroxy-α-phenylsulfenyl ketone 2, derived from S-(+)-carvone, was treated with 2 equivalents of the Wittig-Horner phosphine oxide derivative 6 followed by excess methyl iodide to give a ca. 2 : 3 mixture of the E and Z α-phenylsulfenyl ketones 3a and 3b. The mixture of sulfides was oxidized to the corresponding sulfoxides 3c,d with m-chloroperbenzoic acid. When this mixture refluxed in benzene, elimination of phenylsulfinic acid occurred and the intermediate E diene derivative 4a underwent an intramolecular Diels-Alder reaction to give the trans-octalone 5a, the cis-octalone 5c, and another product believed to be the trans-octalone 5b in a 60 : 28 : 12 ratio. The Z diene derivative 4b was recovered under these reaction conditions. Wolff-Kishner reduction of the octalone mixture gave (-)-α-selinene (10) as the major product along with the cis-octalin II and other unidentified minor products. When the Z diene derivative 4b was heated in toluene at 150°C for 48 h, a mixture of octalones having the same composition as that produced above was obtained. Likewise, when the 2 : 3 mixture of sulfoxides 3c and 3d was heated in toluene at 150°C, the same mixture of octalones was produced. Apparently, at the higher temperature, the Z diene derivative 4b isomerized to the E isomer 4a which ultimately underwent the intramolecular Diels-Alder reaction.

The synthesis of cyclodecane derivatives by intramolecular alkylation of an α-phenylsulfenyl ketone

The acyclis ω-tosyloxy-α-phenylsulfenyl ketone 1 a, derived from R-(−)-carvone, underwent intramolecular alkylation to give the cyclodecenone derivative 2a in good yield. Oxidation of the sulfide to the sulfoxide and thermal elimination of phenylsulfinic acid gave the ketone 8, presumably resulting from Diels-Alder dimerization of the exomethylene ketone 9, as the major product and the endocyclic α,β-unsaturated ketone 7 as the minor product. Reduction of 7 with LAH and treatment of the allylic alcohol product 10 with the sulfur trioxide-pyridine complex followed by LAH gave the (Z),(Z)-1,6-cyclodecadiene 11 and three other minor products, possibly including the sesquiterpene, helminthogermacrene (3). In contrast to the keto sulfoxide 2b, which mainly underwent exo elimination of phenylsulfinic acid, the hydroxy sulfoxide 12b, prepared from ketone 2a, underwent largely endo elimination to give the allylic alcohol 13 containing a (Z),(Z)-1,5-cyclodecadiene system.

The synthesis of 11-oxabicyclo[6.2.1]undecenone derivatives

Abstract 11-Oxabicyclo[6.2.1]undecenone derivatives 16 and 17 were synthesized via cycloalkylation of appropriately substituted monocyclic 3(2H)-furanone derivatives.

A Convenient Synthesis of 7,9,9-Trimethyl-1-oxaspiro[4,5]-6-decen-2-one

Abstract The allylic lactone 1 was prepared from the reaction of lithium 3-lithiopropanoate (5) with isophorone (3) followed by mild acid treatment of the hydroxy acid adduct.

Introduction of an Isopropyl Group at the Gamma Position of a Hydrindenone Derivative

Abstract The oxy hydrindenone derivative 6b was converted stereoselectively into the corresponding γ-isopropyl derivative 10 by a five-step sequence.

Photochemical rearrangements of 6/5-fused cross-conjugated cyclohexadienones in protic solvents

Irradiation of the ring A unsubstituted 6/5-fused cross-conjugated cyclohexadienone (1a) and its 2-methyl derivative (1b) in methanolic acetic acid yields, in addition to other products, novel tricyclononane derivatives which have been assigned the structures (3a) and (3b).

The synthesis and acid-catalysed rearrangement of a spiro[4,5]dec-6-en-2-one

The spiro[4,5]dec-6-en-2-one (3) has been synthesized and found to undergo rearrangement into the octalone (4) upon acid treatment.