The preparation and characterization of di-t-buryl dithiol tricarbonate

Tetrahedron Letters&.55, PP. 5535-5536, 1968. Per8amn Press. Printedia GreatBritain*

'DIEPREPARATI~AND~2ATIONOF DI-t-BUIYL DI'DIIOL TRICARBCMTE A. W. Friederang and D. S. Tarbell Deparbnentof~istry,Vanderbilt~~rsity Nashville, Tennessee37203 (Receivedin USA 24 August 1968; received in UK for publication26 September 1968)

Di-t-butyl dicarbonate II)has been preparedby reactionof potassiunt-butylcationate with phosgenein about5% yield.' In orderto identifythe productsof the decaspositim of the thiolcarbonic phosphoric auhydride 2 2 we attempted to synthesize di-t-butyl dithioldicarbonate (i)by the analogous reactionof sodiunt-butyltiolcarbcmate with phwee

(eq. (1)). R = t-butyl -1

(1) 2 I?,!+CtXBIa + CCC12--3

-

RS-El!&' -0- -0- -SR% 3

I&

4

e-SR -5

We obtainedin good yielda crystalline product(mp 64-67'afterrecrystallization franpentane);

its infraredspectmnshowedthe expectedtwo cazbmylbands. lhe elemental

analysis, however,did not correspond to the dicarbonate Q, but to di-t-butyl dithiol-tricazbonate(2) (calcdfor CllHlgS205:C, 44.8%;H, 6.16;S, 21.78. Fouud: C, 45.08;H, 6.18;S, 21.67),whichwas expectedto be a very mstable intermediate in the abovereacticm (1). The structureof Jwas confirmed by osmomtricmolecular weightdetemination(calcd 294; Fomd: 300 (solvent: benzene))and by cmpariscmof the ir aud nmr spectrawith the

5535

No.55

55%

3, as shawnin the Table. dicarbarate4_andthemonacarbonate~

TABLE: Spectraof Di-t-butyl DithiolCarbarates -mlra

!Tz!E?G tricarbonate 3 dicarbonate4mnocarbonatZ5

-iP

1.55 (s) 1.51 1.47 (s)

183S0~750 1635 1770:'1710

ao-o-a, 920 940 -

avarianA-60,carbontetrachloride solution, lM as internalstandard, 6 (ppn)values. Beckman IR-10,carbontetrachloride solution, wave rnnnbers (an-l). As far as we bnav this is the firstsynthesis of a compomdwith the structure type2. The oxygenanalogof J decasposes insnediately to 1.l Ry contrast, J is mexpectedlystable. If heatedundervacuum to 55' for 7 hcurs;it losesabout405 of its weight;this,however, is due to sublimation andnot

to decomposition, sublimateand residuehavethe samemp and

ir spectraas the startingmaterial. If heatedundervacuumaboveits meltingpoint,e.g. in a bath of 75', 2 decomposes very rapidlyto give the dicarbonate 4 (bp 79-80°/0.05 mm, mp 27-33), whichwas identified by its spectra(Table)and elemental analysis(calcdfor 4 deccmposes c10H18s203:C, 47.97;H, 7.25. Found: C, 48.29;H, 7.53). The dicarbonate to the knm3

monocarbonate Swhen heatedat atmospheric pressurefor 45 min. at 170'.

We are indebtedto.the Nat&ma1

Science Foundation for supportof this work through

Grant8-7874. REFRRENCES (1) J. H. Hare and L. R. MDrris,J. Org. Chem.,27, 1901 (1962). (2) D. S Tarbelland A. W. Frlederang, paperin *aration. (3) L. Wei and D. S. Tarbell,J. Org. C&em.,33, 1884 (1968).