Hydroxy amines oxidative cleavage

Novel nor-seco baccatin 99 was synthesized in 92% yield through oxidative cleavage of the A ring of 14-OH-DAB (75) with periodic acid via the hydroxy ketone intermediate 100 (Scheme 19). Protection of the 7-hydroxyl of 99 as TES ether followed by reduction of the aldehyde with sodium borohydride yielded nor-seco baccatin alcohol 101 in 80% yield. Nor-seco 13-amino-baccatins 102 and 103 were synthesized from 101 and 99a via the Mitsunobu reaction and reductive amination, respectively, in high yields (Scheme 20). 

This reaction has wide application in the analysis of carbohydrate structures and the cleavage of adjacent diols, a-keto alcohols, a-keto acids, and hydroxy amines. In addition, this oxidation also renders a method for preparing aldehydes and ketones. 

Controlled oxidation of the a-pinenes with potassium permanganate leads to the enantiomeric 2-hydroxy-3-pinanones 38 29-31, while under forcing conditions, ring cleavage occurs, leading to cyclobutane derivatives 39. The hydroxy ketones 38 are useful auxiliaries forming imines with benzylic amines or glycine esters which can be alkylated enantioselectively via the enolates (Sections D.l. 1.1.1.3.2., D. 1.1.1.4.1. and D.I.5.2.4.). 

Amino acids. Oxidation of aliphatic primary amines with ruthenium tetroxide leads to complex products. However, oxidation of aralkylamines at pH 3.0 with periodate (12 eq.) and RuCls 3H2O (0.02 eq.) converts the aromatic ring into a carboxyl group to give amino acids. Cleavage is facilitated by a 4-methoxy or hydroxy substituent in the ring. ... 

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