Ylides alkaline hydrolysis

The different evolution possibilities for the alkaline hydrolysis of phosphonium salts are shown together in the general Scheme 1. Two major parts can be distinguished on the one hand, SN(P), SN(P)mig and Ep reactions, which result from the initial attack on the phosphorus atom by hydroxide anion acting as a nucleophile and on the other, EH(X and EHp reactions (and also bearing in mind the formation of phosphonium ylides), which result from the initial attack of the hydroxide anion on the hydrogen in the a- or / -position to the phosphorus. 

The first reported 10-deaza folate analogues were 10-deazaFA (471) and 10-deaza-9,10-dehydroFA (470) [179], Treatment of 2-acetylpterin-6-carbox-aldehyde [464) with ylide (465) furnished (466). Alkaline hydrolysis of (466) and reacetylation gave (468) which was converted to (470) under standard conditions. Catalytic hydrogenation of (466) with subsequent saponification and oxidation produced (467) which was converted analogously to (471) (,Scheme 3.93). 

A new method of fluoro-olefin synthesis involves initial reaction of the ylide-salt (60) with perfluoroacyl fluorides to give vinylphosphonium salts (61), rather than the acylation products. Alkaline hydrolysis of (61) gives ( )-fluoro-alkenes (Scheme 8). The reaction of non-stabilized ylides with chlorodifluoro-... 

Carboxylic acids allenes Alkylidenetriphenylphosphoranes (1) react with ( (>2 to give ylides (2). These are crystalline, but melt with decomposition to give allenes (3) in rather low yield. They are converted into carboxylic acids in high yield on alkaline hydrolysis. 

CT-Telluranes 44 were employed for the synthesis of other derivatives of phenotellurazines with a tricoordinated tellurium atom. The tellurium ylides 46 were obtained in high yields by coupling Te,Te-dibromophenotellurazines with dime-done in the presence of equivalent amounts of EtsN. Alkaline hydrolysis of the dibromides leads to telluroxides 47 in 80-85% yield [82DOK(266) 1164 85KGS757]. 

Thus, treatment of the model ketone 114 with the ylide, generated from 115 under strictly anhydrous conditions, stereoselectively installed the exocyclic double bond (Z/E, 10 1 ratio), leading to the diene 116. After removal of the tosyl protecting group, alkaline hydrolysis followed by macrolactamization of the resulting crude amino acid provided the tricyclic lactam 117. 

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