New 5-Nitrotetrahydro-l,3-oxazines Substituted in Position 2*)

Transcription

1 BLLETIN E L'ACAEMIE POLONAISE ES SCIENCES Série des sciences chiiques Volue V, No., 977 ORGANIC CHEMISTRY New 5-Nitrotetrahydro-l,3-oxaines Substituted in Position 2*) by Hanna PIOTROWSKA, Tadeus RBAŃSKI, Sudesh K. VASEVA**) Presented by T. RBAŃSKI on May 6,.977 Suary. New 5-nitrotelrahydro-l,3-oxaine derivatives were prepared with substituents in position 2, vi. C and CH, and in position 3, vi. CH 2 and H. It was found that copounds with CH 2 C(, in position 3 can be subjected to isoeriation with the N 2 group passing fro the axial to the equatorial position through an action of an aoid catalyst CF,COOH. In continuation of our studies on the derivatives of 5-hitrotetrahydro-l,3-oxaine we have now caed out experients on the preparation of 2- and 3-substituted copounds () which could be used to study their (a) stereocheistry and (b) biological activity (Schee ). ^CH.CftHs CH 2 / $ cis trans (R =, R -CH 2 ) Schee Copounds () were obtained by cycliation with aldehydes (RCHO) of 3-aino- -2-alkyl-2-nitropropanol derivatives substituted in position 3 (2, R'=CH 2 or H,,). So far the cycliation of 2 was successful when position 3 was unsubstituted, i.e. R' = H []. Less studied was the cycliation of 2 substituted in position 3 (2, R' = CH 2 ) [2] and it was soon found that they give lower yields than 3-unsubstituted ainopropanols (2, R' = H) [3]. The reason for the difference in the behaviour of 2 with the priary (R'=H) and secondary aino group will be discussed in one of our next papers. We have now found that the yield of () depends on both substituents R and R', i.e. those in 3-ainoalcohol and in aldehyde used for cycliation, respectively. *) Part CV in the series: Cheistry of Nitroalkanes. **) Post-doctoral Fellow on leave fro Terinal Ballistics Research Laboratory, Chandigarh (India). 3 [779]

2 78 H. Piotrowska et al. 5 i < -o il o' ~ \ \ s Ч rl >п IN r- - VO vd ON ч" r»l ЧГ; С N \ ч СП ON >л * \ Ч ЧП Ч Ч <3\ * l3 ГЧ ч r-' ч» Ч f*l *rî ч ч- ( es СЧ Ч Sr л б $ 9 u. в n n n ГЧ гч M -< rt O M s ж ri г» К fi u. Z M u /-s ш OO s s s n < H Б (Л * 8 i С = S С l J is w. Е. r~ ^. I O ON T С sn OO T ôc гч 3 T3 'C '6 в у 3 h 'S 3 а 9 Е

3 New S-Nitrotetrahydro-lf-oxaines 3 S &. в 5.6 С ro t b? J Щ Ч ю ** a 3 s g, x 8. -* - гп I 4 >n Ч * (*5 ^ С * S 8 CH 2-6 quartet i u SE S S 8 **ï 35 oc sn r- v-> r- (Ś s rs r- * щ rrj щ rń <Ч -*!» <N * ci rrj > 8 * r»i Г OJ 9 СГ -СГ Г4 I J S. ro rn я ri r-i r- r- -> rô r- IN (N <N ГЧ ~i <N Ч rń ON ГГ) rrj <N РЧ С rn N & iri -> rs IS r- r» * cr 9. e *» * * rr, iri in rr, ri С Solvent CC 3 CCIj CCb Nitrobenene Nitrobenene Nitrobenene Copound ^ I ч,» J os os _ к ri В J' a; S - Il J' OS os

4 782 H. Piotrowska et al. Soe properties and analytical data of the cyclied copounds are suaried in Table I. The JR spectra of all copounds show three bands typical of tetrahydro- -,3-oxaines: 43-24, 6-5 and c - characteriing the acetal bond C O C. High intensity bands and c" ' are present in the IR Spectra. They belong to N 2 asyetrical and syetrical stretching vibrations, respectively. One strong band at 455 c" in all the exained copounds is typical of CH, scissoring vibrations. The NMR data are collected in Table II. The ain part of NMR spectra consists of two quartets corresponding to two nonequivalent ethylene groups CH 2-4 and CH 2-6. The quartets are fored by two AB spin systes resulting fro nonequivalence of the protons within each ethylene group. It is worth noting that all equatorial protons are coupled to each other (7=3. cps), as indicated by the splitting of their signals. This ight be due to the coplanarity of the С H tc) and С bonds in the chair conforation of the ring. The high values of S for both CH 2-4 and CH 2-6 indicate the presence of the axial nitro group. Siilar \alues of J ac for both CH 2 groups (ca. 3. cps) also suggest a nearly syetrical orientation of the nitro group with respect to both ethylene groups. The high values of 5 <u, result fro the action of the nitro group upon ethylene protons. The equatorial protons are closer to the nitro group than the axial ones and subsequently the forer are probably strongly deshielded and the latter only slightly affected. The ethylene group of the benyl substituent in position 3 gives a quartet. It should be pointed out that under the conditions described in the Experiental we were not able to obtain copounds () by cycliation of 2, when: (a) R' in 2 was CH 2 C h, and />-nitrobenaldehyde was used for cycli/ation (R=/>-N 2 H 4 ), (b) R' in 2 was H,, and benaldehyde or p-nitrobenaldehydc were used for cycliation. They probably require odified experiental conditions and this proble, too, will be discussed in our next papers. ^ 4^R 2 N\ ^CH 2 OH c : 2 N. ' C N. С-Ц ^CH 2 -NH CH 3 Л 2 Schee 2 cis-trans-isoeriation of I, R = C b H s, R' = CH 2 C b. When 2-phenyl-3-benyl- -5-ethyl-5-nitrotetrahydro-l,3-oxaine was dissolved in nitrobenene and a catalytic aount of trifluoroacetic acid was added, the NMR spectru changed to show two coalescing ethyl (5) singlets which indicate an equilibriu around the carbon

5 ato with the nitro group, as shown in Schee. The presence of two isoers was detected by TLC, the cis/trans ratio being equal to 45/55. If the solution was neutralied, only the trans isoer was found after a few hours. A siilar isoeriation was found with R=CH 3, R'=CH,C (, but with a saller aount of the eis isoer (ca. 5%). No such phenoenon was observed with copound, R=CH,, R'= H,,. 783 Experiental 2-Methyl-i-bcnyl (unci cyclohexyl)-2-nitropropanols (2) were prepared according to the known ethod [3]. Cycliation of 2 (R'--CH 2 C b H f and С ь Нц) to copounds. Copound 2 (R'^CH 2 and H n ) (. ole) was dissolved in benene (3 l) and freshly distilled benaldehyde or acetaldehyde (. ole) was added along with a sall aount of sodiu bicarbonate (5 g). The solution was refluxed for 5 h and benene (together with the fored water) was then distilled was extracted with hot benene and sodiu bicarobnate was filtered off. Benene solution was evaporated under reduced pressure. The white sol idof (R=, R' = CH 3 ; R = CH 3, R^ÇsH,,) was crystallied (see Table ). When, R=CH 3, R'=CH 7 C was obtained the oily residue was distilled under reduced pressure. One of the authors (S.K.V.) thanks the Ministry of "Education and Social Welfare New elhi (India) for the financial support. INSTITTE OF ORGANIC CHEMISTRY AN TECHNOLOGY, TECHNICAL NIVERSITY. KOSZYKOWA 75, -662 WARSAW (INSTYTT CHEMII I TECHNOLOGII ORGANICZNEJ, POLITECHNIKA WARSZAWSKA) REFERENCES [] T. rbański, H. Piotrowska, Bull. Acad. Polon. Sci., Cl. III, 3, 389 (955); Rocnik Che., 3, 553 (957). [2] Z. Eckstein, W. Sobótka, T. rbański, Rocn. Che., 3, 33 (956); 3, 347 (957). 3] T.rbański, Synthesis, 974, 63. Г. Птрвка, Т. Урбаньк, С. К. Ваудва, Нвые 5-шпртетрагдв-,3-казнны замещенные в пзц 2 Сдержане. Плучены нвые прзвдные 5-нтртетрагдр-,3-казна заметтелям в пзц 2 (СН, CH.,) в пзц 3 (CoHjCHi С 6 Нц). Утанвлен, чт едненя группй С 6 Н,СН 2 в пзц 3 мгут быть змерзваны, пр этм группа NO ; перехдт з акальнй в экватральную пзцю. Измерзаця прхдт пд дейтвем клтнг каталзатра -CFjCOOH.