Monothioacetals, cyclic

Monothioacetals, cyclic, protection of carbonyl groups as - 27, 271 Monothio-j3-diketones... 

Monoperphthalic acid s. Perphthalic acid Monothioacetals, cyclic... 

In a more recent study (104), similar results were obtained with the bicy-clic thiol hemiacetal 75 (Fig. 13). Cyclization of 75 under kinetically controlled conditions gave the ci monothioacetal 76 the trans isomer 77 was not observed. Thus the attack of an SH group on a cyclic oxonium ion must also take place preferentially with stereoelectronic control. 

Formation of spiro orthoesters such as 4 is achieved in high yield by reaction of cyclic ketene monothioacetals such as 3 with ethanediol and camphorsulfonic acid <04SL2013>. A variety of substituted epoxy ketones 5 rearrange to the benzodioxoles 6 upon treatment with Bu.,N CN in CHjClj or K1 in acetone <04T3825>. Condensation of phenacyl carbonates 7 with aromatic aldehydes in the presence of MgCClO ), 2,2 -bipyridyl, A-methylmorpholine and molecular sieves gives the trans dioxolanones 8 <04SL1195>. 

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