New approach to the synthesis of(R)-3-methyl-?-butyrolactone

Kharisov, R. Ya.; Latypova, E. R.; Талипов, Р. Ф.; Ishmuratov, G. Yu.; Толстиков, Г. А.

doi:10.1007/s10600-005-0015-0

Cited by 3 publications

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“…Stereospecific Beckmann rearrangement always involves that group which is located in the anti position with respect to the hydroxy group [12]. The corresponding group in (Z)-O-tosyloxime XI is C 7 H with sp 2 -hybridized carbon atom, which is not capable of migrating (as in menth-4-en-3-one oxime [15]). Therefore, (Z)-O-tosyloxime XI remains unchanged under the above conditions.…”

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20-hydroxyecdysone oximes and their rearrangement into lactams

et al. 2009

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E)-Oximes derived from 20-hydroxyecdysone diacetonides and 7,8-dihydro analog were converted into the corresponding lactams (6-oxo-5a-aza-5a-homo derivatives) via Beckmann rearrangement. 14,15-Anhydro-20-hydroxyecdysone (Z)-oxime under analogous conditions (reaction with p-toluenesulfonyl chloride in acetone in the presence of Na 2 CO 3 ) gave rise to 20-hydroxyecdisone 20,22-acetonide (Z)-O-tosyloxime which did not undergo Beckmann rearrangement.Oximes are widely used in organic synthesis, and they exhibit diverse biological activity [1]. In the recent years, interest in oximes of the steroid series considerably increased [2,3]. This interest was stimulated primarily by the isolation of steroidal oximes from the marine sponges Cynachyrella alloclada and S. apion [4]. which, like their synthetic analogs [5], turned out to effectively inhibit aromatase (the key enzyme in the biosynthesis of estrogens) and attracted attention as potential antitumor agents [6]. Ecdysteroid oximes and their chemical properties have been studied poorly. We previously reported on the synthesis of 20-hydroxyecdisone oxime and the corresponding diacetonide [7].In the present work we succeeded in effecting Beckmann rearrangement of (E)-oximes II and V derived from 20-hydroxyecdysone and its 7,8-dihydro analog with a view to transform the ecdysteroid B ring into seven-membered lactam ring, a fragment intrinsic to azabrassinosteroids [8].By treatment of 20-hydroxyecdysone diacetonide I with hydroxylamine hydrochloride in pyridine we obtained a mixture of the corresponding (E)-and (Z)-oximes II and III (Scheme 1) [7]. The oximation of 7,8-dihydro-20-hydroxyecdysone diacetonide IV under analogous conditions gave (E)-oxime V (Scheme 2). When the oximation product of 7,8-dihydro analog IV was treated with a solution of potassium hydroxide in ethanol, we obtained 14,15-anhydro-7,8-dihydro-20-hydroxyecdysone diacetonide (E)-oxime VI. An attempt to reduce the latter into 7,8-dihydro-14-deoxy-20-hydroxyecdysone diacetonide oxime by catalytic hydrogenation over Raney nickel resulted in the formation of 7,8-dihydrostachysterone B diacetonide VII (Scheme 3). The 13 C NMR spectrum of VII was fairly similar to the spectrum of 7, 8-dihydrostachysterone B 20,22-acetonide [9], and some differences were related to the presence of an additional O,O′-isopropylidene protective group at positions 2 and 3 of compound VII.The structure of oximes V and VI was confirmed by the 1 H and 13 C NMR spectra. The signals were assigned using one-( 1 H, 13 C, APT) and two-dimensional correlation techniques (COSY, HSQC, HMBC). In the 13 C NMR spectra of oximes V and VI, the α-methylene carbon atom (C 7 ) resonated in a stronger field (δ C 26.18 and 26.16 ppm, respectively) than the C 5 atom (CH, δ C 42.28 and 42.48 ppm), indicating their syn (C 7 ) and anti (C 5 ) orientation with respect to the N-OH group. This means that oximes V and VI have E configuration [7, 10].Oximes of the ecdysteroid series did not undergo Beckmann rearrangement under conditions of acid catalysis. ...

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20-hydroxyecdysone oximes and their rearrangement into lactams

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“…This fact followed from experimental found increase of stereoselectivity of 1,4-nuclophilic addition to (R)-4-menthen-3-one with temperature growing [4][5][6]. Taking into account this interesting facts we believe (R)-4-menthen-3-one is not only useful and important compound for the synthesis of a wide range of pheromones [7][8][9][10][11][12][13][14][15][16][17][18][19] and chiral synthons [8,12,20], but interesting object, which can help to investigate correlation between electronic structure and internal rotation and inversion.…”

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confidence: 86%