3- thioethers 1.3- dithianes, synthesis

The use in organic synthesis of carbanions stabilized by one or more adjacent thioether groups is now a well-established technique [272-275]. A landmark in this development was the work of Corey and Seebach on 1,3-dithianes [276]. They pointed out the use of the anions of 1,3-dithianes as... 

Synthesis of 3-(acylthio)thioethers from 1,3-dithianes and trialkylalanes... 

Crown thioether chemistry dates from 1886, when Mansfeld reported the synthesis of 9S3 [40]. To determine whether ring sizes greater than six could be prepared ( ) he allowed ethylene bromide to react with sodium sulfide. From this reaction he isolated a product that differed in properties from p-dithiane he suggested it might be 9S3 (Table 4). A similar procedure with 1,3-dibromopropane led to a compound tentatively proposed to be 12S3. 

Microbial reduction of thioaldehydes resulted in the formation of thiols thus thioac-etaldehyde gave ethanethiol [143,144], and from thiobutyraldehydes the corresponding thiols were obtained [145]. While thioethers were cleaved [146], thioacetals were stable. Thus, compoimd 24 (Figure 21.9) was reduced with an ee of 99% to (S)-l-(l,3-dithian-2-yl)-2-propanol 25, a central intermediate for the synthesis of (S,S)-grahamimycin A1 [147]. 

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