Desulfonylation Lithium-Ammonia

Desulfonylation Lithium-Ammonia, 158 Lithium triethylborohydride, 168 Magnesium-Methanol, 170 Sodium dithionite, 281 Sodium naphthalenide, 294 Desulfurization Lithium aluminum hydride-Bis(cyclopentadienyl)nickel, 158 Lithium l-(dimethylamino)naph-thalenide, 165 Lithium-Ethylamine, 158 Dethioacetalization (see Hydrolysis of thioacetals and -ketals)... 

For the synthesis of aza-thia macrocycles, many of the methods that are available for the synthesis of aza cycles (Chapter 2) or aza-oxa crowns (Chapter 3) are also applicable. Thus the Richman-Atkins co-cyclisation of the ditoluenesulfonamide with an alkylditoluenesulfonate may be used for the synthesis of the [18]-N4S2 ring (Scheme 3.6). In this case, desulfonylation to afford the tetraamine 23 is best carried out with lithium in liquid ammonia.12... 

Synthesis of (—)-Lasubine II. A reductive desulfonylation with lithium in ammonia is employed in the total synthesis of quinolizidine alkaloid (—)-lasubine II.264 A conjugate addition of methyl (.S )-(2-pipcridyl)acetate to an acetylenic sulfone, followed by lithium diisopropylamide (LDA)-promoted intramolecular acylation is the key step in the preparation of the quinolizine structure of (—)-lasubine II (Eq. 154). 

Reductive desulfonylations and reductive eliminations can be performed employing alkali or alkaline earth metals in ammonia or low molecular weight amines. Lithium or sodium in ammonia or ethylamine are very effective systems... 

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