I'm passing along this query from a synthetic organic chemist colleague. Any
comments from you clever small molecule spectroscopists out there would be
most appreciated.
Regards,
Donna
--------------------------------------------------------------------------------Donna Baldisseri, Ph.D. |Internet: baldisse@waltz.ab.umd.edu
UMB, School of Medicine |Internet: dbaldiss@umaryland.edu
Health Sciences Facility, Rm 153 |Phone: (410) 706-8335 FAX: 6-0938
685 W. Baltimore St. |"Just because you're paranoid doesn't
Baltimore, MD 21201 | mean they're not out to get you."
###############################################################################
We began our synthesis with the known compound
3,3,10,10-tetramethyl-1,2-dithia-5,8-diazacyclodecane. 1H NMR:
(300MHz, CDCl3) 1.20 (6H,s), 1.33 (6H,s), 2.53 (d, 2H, J=12.8Hz),
2.77 (s, 4H), 2.96 (d, 2H, J=12.8Hz). Apparently in this compound
each member of the respective pairs of geminal protons at the 4 and 9
positions and each member of the pairs of geminal methyls at the 3 and
10 positions is not equivalent to its positional mate. We treated
this material with one equivalent of di-t-butyl dicarbonate (t-boc
anhydride) and isolated the major component as a pure fraction by
column chromatography. In the NMR spectrum of the product, the
general appearance and integration are consistent with a product
bearing a single t-boc group on one of the nitrogen atoms, but the
extreme broadness of some signals makes definitive assignment
difficult. 1H NMR: (300MHz, CDCl3) 1.23 (6H, s), 1.24 (3H, s), 1.29
(3H,s), 1.44 (9H, s), 2.43 (1H, d, J=12.3Hz), 2.75 (1H, br d,
J=11.5Hz, linewidth = 22Hz), 3.00 (1H, d, J= 12.3Hz), 3.05 (1H, m),
3.52 (1H, br ?, linewidth = 49Hz), 3.69 (2H, br ?, linewidth = 31Hz),
4.4-5.1 (1H, broad blob with 2 maxima which appears to be a single
proton having two chemical shifts, linewidths = 32 Hz). We would
appreciate any insight into what is going on with this product, since
we have never seen such broad resonances in the room temperature
spectrum of a purely organic compound.
Carol Lambert, Ph.D.
Diagnostic Radiology
Division of Nuclear Medicine
University of Maryland Medical Center
22 S. Greene Street
Baltimore, MD 21201-1595
Phone 410 706-8714
###############################################################################