Reaction of rotenone with boron tribromide. Stereospecific²H-labelling of (–)-rotenonic acid in the 4′(E)-methyl group

Abstract

Structural revisions are made to products IT has recently been reported that reaction of natural formed when (-)-rotenone is treated with boron tri-(6aS,12aS,5'R)-(-)-rotenone (1) with 1 mol. equiv. of bromide; stereospecific labelling of the 4' ( E ) methyl of BBr, gives the 1',5'-seco-bromide (2), whilst with 2 mol. (-)-rotenonic acid, a biosynthetic precursor of rotenone, equiv. of BBr, gives (3).ls2 Treatment of (2) with HC0,can be achieved by treating product (4) with cyano-provides the only method available for making (5's)borodeuteride in hexamethylphosphorotamide.rotenone, which is formed along with the (5'R)-diastereoisomer. However, structures (2) and (3) appeared a t

Hydroxylated Rotenoids Selectively Inhibit the Proliferation of Prostate Cancer Cells

“…52,53 Next, rot-2′-enonic acid (25) was prepared from rotenone (1) as described previously (Scheme 3). 54 The isomericrot-3′enonic acid (26) was also prepared from 1 (Scheme 3) by ring opening with BBr 3 , 55,56 to give 4′-bromorot-2′-enonic acid (see Experimental Section), and reaction with activated zinc powder and NH 4 Cl in aqueous THF.…”

“…This was prepared by adapting several literature procedures. , The following procedure gave consistently reproducible results: BBr 3 (2.54 mL of a 1.0 M solution in CH 2 Cl 2 , 2.54 mmol) was added dropwise over 10 min to a solution of 1 (1.00 g, 2.54 mmol) in dry CH 2 Cl 2 (6.0 mL) under N 2 at −20 °C. The mixture was stirred at −20 °C for a further 20 min before the reaction was quenched with H 2 O (20 mL), quickly warmed to rt, and extracted with EtOAc (20 mL).…”

Rotenoids and their biosynthesis

“…19q20 The biosynthetic parent of this group of rotenoids, i.e. (&)-9-demethylmunduserone (39), was made in radiolabelled form by similar methods, starting from 7-benzyloxychromanone (34), and employing tritiated dimethylsulphoxonium methylide (formed from the sulphonium salt, T20, and base). This method gave, via (37), ( &)-9-demethylmunduserone that was tritiated at C-6; the use of the latter in biosynthetic experimentation is mentioned later.…”

“…Our work thus shows that prenylation and subsequent modifications to form ring E of amorphigenin occur after closure of ring B to form a rotenoid. Such a situation places 9demethylmunduserone (39), on proven biosynthetic grounds, in a key position as the parent of the sub-family of rotenoids having 2,3-dimethoxylation in ring A and resorcinol oxygenation in ring D. This arrangement was used in Table 1 at the outset of this account, and it is logical to classify the other known rotenoids under the three sub-families shown there (whilst acknowledging that there may be still others). To finally…”

Stereocontrolled semi-syntheses of deguelin and tephrosin

“…1 ) was reported by Anzeveno in 1979, 9 building upon Unai, Yamamoto and Crombie's earlier works on the selective E-ring cleavage of rotenone. 10 , 11 The key intermediate in the synthesis was rot-2′-enonic acid 5 ( Scheme 1 ), however its preparation involved the reductive dehalogenation of an allylic bromide with sodium cyanoborohydride in neat hexamethylphosphoramide. 9 …”