Oxazolidine-2-thione, -4-ethyl

To increase the yields of the ring closure reactions, a new method was developed that was successfully applied for the synthesis of alicyclic fused systems of both the parent oxazolidine-2-thione and tetrahydro-1,3-oxazine-2-thione (85S1149). As an example, the synthesis of 2-thioxoperhydro-l,3-benzoxazine 103 is described. The dithiocarbamate 101, prepared from the amino alcohol 100, carbon disulfide and triethylamine, was treated with ethyl chloroformate in the presence of triethylamine, to give the thioxo derivative 103 via the transition state 102 (85S1149). In this way, the fused-skeleton thioxooxazines (91, X = S, 92) can be prepared with considerably higher yields (50-70%) than by the earlier methods (85S1149). 

Other C4-chiral oxazolidine-2-thiones. (45)- (2) and (4i )-ethyl-l,3-oxazolidine-2-thione (3) [(45)- and (4/ )-EOT], (45)-isopropyI-l,3-oxazol-idine-2-thione (4), and (4/ )-methyl-(55)-phenyl-l,3-oxazolidine-2-thione [(4/ ,55)-MPOT] (5) were likewise synthesized. Typical preparations of C4-chiral l,3-oxazolidine-2-thiones (2-5) from )3-amino alcohols (6-9) are as follows. 

Related Reagents, S or /5 4-Ethyl-l,3-thiazolidine-2 thlone S or 7 4 Methoxycarbonyl-l,3-thiazolidine-2-thlone (. 4 Methoxycarbonyl-l,3-thiazolidine-2-selenone (. 4 MethoxycarbonyTl,3 oxazolidine-2-thione (, -4-Iso-propyTl,3 oxazolIdlne-2 thlone S or 75 4-Ethyl-l,3-oxa-zolldlne 2 thlone (7 4 methyl-(5)-5-Phenyl-l,3-oxazolidine-2 thlone (, -4-(phenylmethyl) l,3-thiazolidine-2-thione, ... 

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