R E G I O S E L E C T I V E S Y N T H E S I S OF ~ -

A N D ~ ' - S U L F U R - C O N T A I N I N G E T H Y L E S T E R S

O F D E H Y D R O D E S T H I O B I O T I N

S. I . Z a v ' y a l o v , O. V. D o r o f e e v a , a n d N. A. R o d i o n o v a

UDC 542.91:547.9:577.15

The a - and a ' - s u l f u r - e o n t a i n i n g de r iva t ives of dehydrodesthiobiotin p o s s e s s in t e re s t as poss ible bio- p r e c u r s o r s of v i t amin H [1, 2].

To study the biological p r o p e r t i e s of this type of compound we developed a reg iose lec t ive method for the thiylation of the ethyl e s t e r s of a - and ~ ' -oxodehydrodes th iobio t in (I) and (IV) at the keto and aldehyde groups.

0 0 II 11

HN/r~NH AcSH, BI~,_. H N ~ N H

H,0 ~ R

CH3 COB CHa C=S (I) (II)

B = (CHe)4COOEt

0

A Ni HN NH

CH3 CHaR (III)

The reac t ion of ke toes t e r (I) with AcSH in the p resence of BF 3 gave the ethyl e s t e r of ~- th iooxodehydro- desthiobiotin (II) in 45% yield, whose s t ruc tu re was proved by the e lementa l ana lys is , spec t ra , and chemical t r ans fo rma t ions . In f r a red spec t rum of (II) (v, cm-1): 1725 (COOEt), 1705 ( imidazol in-2-one ring), 1670 (C----S). P1VIR s p e c t r u m of (H) (CDCIs, 6, ppm): 1.13 t (CH2CHs), 1.63 m (CH2CH2) , 2.23 m (CH2C=S) , 2.33 s (CHaC=C) , 2.97 m (CH2C ---- O) , 4.00 q (OCH2).

The hydro lys i s of (II) conver ts it to the s ta r t ing ke toes te r (I) with the l iberat ion of H2S, while desu l fur - ization with Raney nickel conver ts it to the ethyl e s t e r of dehydrodesthiobiotin (III).

The thiylation of the i s o m e r i c ethyl e s t e r (IV) p roceeds differently, and it r e ac t s with AcSH and BF s to give the ethyl e s t e r of a ' , ~ ' - d i ace ty lmercap todehydrodes th iob io t i n (V) in ~ 80% yield.

o o I! II

HN/~NH AcSH, BF~ HN/'~N H

0He R (SAc)2HC R (IV) (V)

. R = (CH:)sCOOEt

The structure of (V) was confirmed by hydrolytic cleavage to the starting aldehyde-ester (IV), and also by the elemental analysis and IR and PM!R spectral data. Infrared spectrum of (V) (v, cm-1): 1730 (COOEt), 1710 (imidazolin-2-one ring), 1680 (SAc). PMR spectrum of (V) (CsD~N, 6, ppm): 1.00 t (CH2CHs), 1.26 m (CH2CH2CH2), 1.93 m (CH2C =O), 2.01 s (2CHsCOS), 2.23 m (CH2C=C) , 3.85 q (OCH2), 6.46 s (C=CCH (SAc)2). The UV spectrum of (V) is devoid of intense absorption maxima in the 300 nm region [3], which testifies to the absence of an aldehyde group, conjugated with the iniidazolin-2-one ring, in the (V) molecule.

The different behavior of oxoes te r s (I) and (IV) when reac ted with AcSH can be explained in the following manner . Apparent ly , under the influence of BFs, the t~- and ~ ' - c a r b o n y l groups of (I) and (IV) each initially add one AcSH molecule to give the semi th ioace ta l s (VD and (VII). Subsequently, under the influence of a second A c ~ t molecule , semithioacyla l (VH) is converted to thioacylal (V). In cont ras t to (VII), the i s o m e r i c

N. D. Zelinskii Inst i tute of Organic Chemis t ry , Academy of Sciences of the USSR, Moscow. Trans la t ed f rom Izves t iya Akademii Nauk SSSR, Ser iya Khimicheskaya, No. 4, pp. 954-956, April , 1978. Original a r t ic le submitted August 24, 1977.

828 0568-5230/78/2704-0828S07.50 �9 1978 Plenum Publishing Corpora t ion

semithioacylal (VI) is cleaved to thioketone (If), since an electron-donor and bulky substituent is found on the electrophilic G-C atom of (VI), which hinders the reaction of (VI) with a second AcSH molecule.

(I~ ~IxG

i_,v,'i;~ j b ~

CH~ ]l HC(SCOCHa}I S

EXPERIMENTAL

The IR spectra were taken as KBr pellets on a UR-10 instrument, the PMR spectra were taken on a DA-60-1L instrument (internal standard HMDS), and the UV spectra were taken in alcohol solution on a Specord UV-VIS instrument. The TLC was run on Silufol UV-254 with development of the spots in UV light and with iodine vapors.

Ethyl Ester of ~-Thiooxodehydrodesthiobiotin (II)o A mixture of 6 g (0.025 mole) of the ethyl ester of G-oxodehydrodesthiobietin (I) [4], 6 ml (0.08 mole) of AcSH, and i0 ml of BF3" Et20 was kept for 360 h at 20~ and then, with stirring and cooling in ice, it was poured into NaHCO 3 solution. The obtained oil was extracted with ethyl acetate (EA) and then chromatographed on a column packed with SiO 2 (L 100/160 m, Chemapol). The impurities were first eluted with benzene, and then elution With EA gave 2.8 g (45%) of (If) as brown crystals with mp 133-135 ~ (after washing with ether), mp 135-136 ~ (from benzene), Rf 0.85 (3 : 2 EA-alcohol). Ultra- violet spectrum ~max 386 nm. Found: C 53.38; H 6.50; S 12.09; N I0.01%. C12HlsN2OsS. Calculated: C 53.32; H 6.7i; S 11.86; N 10,36%.

A mixture of 0.2 g of (II) and 1 g of Skeletal Ni in 10 ml of alcohol was refluxed for i0 h, after which the filtrate was evaporated in vaeuo and the residue was recrystaliized from alcohol, The ethyl ester of dehydrodesthiobiotin (III) With mp 189-191 ~ was obtained, whid~ did not depress the mixed melting point with an authentic sample [5]. Thioketone (If) when heated with water (i00 ~ I0 rain) is converted to ketoester (I).

Ethyl Ester of ~',G'-Diacetylmereaptodehydrodesthiobiotin (V). A mixture of 0.8 g (0.0032 m01e) of the ethyl ester of ~'-oxodehydrodesthiobiotin (IV) [3], 2 ml (0.026 mole) of AcSH, and 1 ml of BF3" Et20 was kept for 360 h at 20 ~ and then it was poured into Na2CO S solution and extracted with EA. After drying the extract over MgSO 4 and removing the solvent we obtained 0.93 g (77%) of (V), rap 130-131 ~ (from alcohol), Rf 0.35 (2:1 acetone-benzene). Ultraviolet spectrum: X max 232 nm. Found: C 50.08; H 6.33; s 16.52%. CIGH24N2OsS~ Calculated: C 49.68; H 6.22; S 16.56%. Thioacetal (V) when heated With water (i00 ~ i0 rain) gives the start- ing aldehyde-ester (IV).

CONCLUSIONS

The ethyl esters of v~- and ~'-oxodehydrodesthiobiotin when reacted With thioacetic acid in the pres- ence of BF 3 etherate respectively give the ethyl esters of a-thiooxo- and G',ce'-diacetyimercaptodehydro- de sthiobiotin.

IQ

2. 3.

LITERATURE CITED

A. Lezius, E. Ringelmann, and F. Lynen, Biochem. Z., 336, 510 (i963). S. Io Zav'yalov, O. M. Radul, and N. A. Rodionova, Izv. Akad. Nauk SSSR, Ser. Khim., 1973, 2626. S. I. Zav'yalov, N. Ao Rodionova, and E. P~ Gracheva, Izv0 Akad. Nauk SSSR, Ser. Khim., !972, 2025.

829

4.

5. R. Dushinsky and L. A. Dolan, J. Am. Chem. Soc., 67, 2079 (1945). S. I . Zav 'ya lov , E. P. Gracheva , N. A. Rodionova, Z. S. Volkova, Yu. B. Vol 'kenshte in , T. A. Stankevich, U. Ya. Miksta is , S. Ya. Miksta, and V. V. Fil ippov, Izv. Akad. Nauk SSSR, Ser. Khim., 1973, 221.

C O R R E L A T I O N B E T W E E N A D S O R P T I O N

H E A T S A N D C H A N G E I N U N I T C E L L

P A R A M E T E R S OF Z E O L I T E C a A D U R I N G

T H E A D S O R P T I O N OF W A T E R V A P O R

V. P . B a r a n o v a , M. M. D u b i n i n , T . N. I v a n o v a , a n d A. A. I s i r i k y a n

UDC 541.183

F r o m the t ime that the phenomenon of a change in the size of the carbon adsorbent during the adsorpt ion of CO 2 was d i scove red [1], the hypothesis that the adsorbent is iner t during adsorpt ion was refuted and many a t t empts were made to es tab l i sh a re la t ion between the deformat ion of the adsorbent during adsorpt ion and the change in the t he rmodynamic p a r a m e t e r s of the adsorption sys tem. The most widespread was the Bangham equation [2], which r e l a t e s the deformat ion to the change in the f ree energy of the adsorba te . The mos t p r o - found ana lys i s of th is p rob lem was made in [3]. However , up to now a theory is lacking that exhaust ively explains the given phenomenon and es tab l i shes a quanti tat ive relat ion between the change in the size of the adsorben t and the t he rmodynamic p a r a m e t e r s of the adsorpt ion sys tem. We feel that es tabl ishing all of the poss ib le co r re la t ions between the deformat ion and the other va r iab le p a r a m e t e r s of the sy s t em or molecu la r m e d l a n i s m of adsorpt ion will be of g rea t help in creat ing a universa l theory of the given phenomenon.

The purpose of the p re sen t paper was not only to es tabl ish a cor re la t ion between the deformat ion (change in p a r a m e t e r s of the unit cell) and adsorpt ion heat of wa te r vapor on zeoli te CaA, but a lso to d iscuss the mechan i sm of adsorp t ion f rom the standpoint of the e l emen ta ry react ion ac ts of the adsorba te molecules with the exchange cations and the i r penetra t ion into sodali te cel ls . It is known that the unit cell of the divalent ion-exchange f o r m s of a type A zeoli te contains 6 exchange cations, in which connection, on the average , two hexagonal r ings in a la rge zeoli te cavity r e m a i n f ree and can faci l i tate an e a s i e r penet ra t ion of fine po la r molecu les (HzO ,Nt I s) into the smal l cavi t ies .

EXPERIMENTAL

For the study we took a CaA sample that was obtained by treating powdered zeolite NaA, produced by the Gorkii Experimental Plant of the VNIINP, with 40% CaCI 2 solution for 24 h, with periodic stirring, at

20~ (solution : zeolite ratio ~ 10 : I). The obtained CaA sample was washed with dilute Ca(NOn) 2 solution by decantation until CI- ion was absent. The chemical analysis corresponded to the formula 5CaO. N20. 6A1203 �9 12.6 SiO z. The calorimetric measurements of the water vapor adsorption heats were run on a molded CaA specimen. The postulated composition of the unit cell of the latter CaA specimen, obtained from the given ion exchange isotherms [4], corresponded to the formula 6CaO" 6A1203" 12SiO 2.

For the x:ray studies the powdered CaA samples were placed in thin-walled Pyrex glass capillaries and sealed to the adsorption equipment, which was equipped with a McBain-Bark balance. The evacuation of the samples in the capillaries and on the pan of the balance was run in parallel at 350 ~ for ~ i0 h. Using the method given in [5], we obtained the relationship of the parameters of the unit cell for different degrees of filling the adsorption space on the same zeolite sample. The preliminary data for the calorimetric adsorp- tion heats of water vapor on molded zeolite CaA are given in [6].

DISCUSSION OF RESULTS

The energy studies of the sorption of water vapor on zeolite CaA disclosed that the aqua complexes Ca 2+ �9 H20 are formed initially, with a high energy of the ion-dipole interaction of ~ 21 kcal/mole. Then

Insti tute of Phys ica l Chemis t ry , Academy of Sciences of the USSR, Moscow. Trans la ted f rom Izves t iya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 956-959, Apri l , 1978. Original a r t i c l e submitted September 1, 1977.

830 0568-5230/78/2704-0830807.50 �9 1978 Plenum Publishing Corpora t ion