Hydroxy amines allyl alcohol

The method is not restricted to secondary aryl alcohols and very good results were also obtained for secondary diols [39], a- and S-hydroxyalkylphosphonates [40], 2-hydroxyalkyl sulfones [41], allylic alcohols [42], S-halo alcohols [43], aromatic chlorohydrins [44], functionalized y-hydroxy amides [45], 1,2-diarylethanols [46], and primary amines [47]. Recently, the synthetic potential of this method was expanded by application of an air-stable and recyclable racemization catalyst that is applicable to alcohol DKR at room temperature [48]. The catalyst type is not limited to organometallic ruthenium compounds. Recent report indicates that the in situ racemization of amines with thiyl radicals can also be combined with enzymatic acylation of amines [49]. It is clear that, in the future, other types of catalytic racemization processes will be used together with enzymatic processes. 

The cyclohexene 121, which was readily accessible from the Diels-Alder reaction of methyl hexa-3,5-dienoate and 3,4-methylenedioxy-(3-nitrostyrene (108), served as the starting point for another formal total synthesis of ( )-lycorine (1) (Scheme 11) (113). In the event dissolving metal reduction of 121 with zinc followed by reduction of the intermediate cyclic hydroxamic acid with lithium diethoxyaluminum hydride provided the secondary amine 122. Transformation of 122 to the tetracyclic lactam 123 was achieved by sequential treatment with ethyl chloroformate and Bischler-Napieralski cyclization of the resulting carbamate with phosphorus oxychloride. Since attempts to effect cleanly the direct allylic oxidation of 123 to provide an intermediate suitable for subsequent elaboration to ( )-lycorine (1) were unsuccessful, a stepwise protocol was devised. Namely, addition of phenylselenyl bromide to 123 in acetic acid followed by hydrolysis of the intermediate acetates gave a mixture of two hydroxy se-lenides. Oxidative elimination of phenylselenous acid from the minor product afforded the allylic alcohol 124, whereas the major hydroxy selenide was resistant to oxidation and elimination. When 124 was treated with a small amount of acetic anhydride and sulfuric acid in acetic acid, the main product was the rearranged acetate 67, which had been previously converted to ( )-lycorine (108). 

Alkyl-4-oxo-l,3-dioxolanes, to protect a-hydroxy carboxy groups, 267 5-Alkyl-4-oxo-l,3-dioxolanes, to protect a-hydroxy carboxy groups, 267 4-Alkyl-5-oxo-l,3-oxazolidines, to protect carboxy groups, 266-267 Allyl alcohols, to protect, 18 iV-Allylamides, to protect amides, 154, 397 /V-Allylamines, to protect amines, 362 Allyl carbamates, to protect amines, 248, 252, 331-332... 

This reaction, which is related to the well-known amine oxide pyrolysis, involves a syn elimination of the selenenic acid, but proceeds under milder conditions (20 C to 60 C instead of 400 C). It is more regioselective, takes place away from the oxygen and leads to allyl alcohols instead of enols, except when the only available hydrogen is the one a to the hydroxy group (Scheme 173, b). ... 

To allow for a diverse multi-step synthesis, we transformed the 3-hydroxy-2-methyl-idene propionic acids (Fig. 6.9) into polymer-bound allylic amines, which can be considered as unusual (3-amino acid derivatives. The polymer-bound allylic alcohols were first treated with acetyl chloride and DIEA in CH2C12 to form the ester, which was reacted with primary amines in an addition elimination step to form allylic amines. 

The allylic alcohol was subjected to an Eschenmoser-Claisen rearrangement with dimethylacetamide dimethylacetal to introduce the C14 substituent in a stereoselective manner. Reduction of the amide to the corresponding aldehyde with phenyl silane in the presence of Ti(0/Pr)4 was followed by an acid-promoted closure of the C-ring of codeine. In order to prevent N-oxidation, the amine was converted to the corresponding tosylamide, via debenzylation and treatment with tosyl chloride, before the allylic alcohol was introduced by the reaction of the alkene with selenium dioxide (65). The stereochemistry of the C6 hydroxy functionality was corrected by applying the well-known oxidation/reduction protocol [46, 60] before the benzylic double bond was reductively removed under Birch conditions. Codeine (2) was obtained in 17 steps with an overall yield of approximately 0.6%. 

Friedel-Crafts alkylations of arenes with mesylates, benzyl or allyl alcohols, aldehyde/diol combinations (reductive alkylation), 1,3-dienes, or alkenes in an ionic liquid are also effectively catalyzed by Sc(OTf)3. Sc(OTf)3 works as an efficient catalyst for the condensation reaction of trimethylhydroquinone with isophytol to afford a-tocopherol. 2-Aminoalkylation of phenols with a-iminoacetates (or glyoxylate/amine) is catalyzed by Sc(OTf)3 to produce amino acid derivatives. The Sc(OTf)3-catalyzed alkylations of indoles with a-hydroxy esters, aziri-dines, acetals, and aldehydes have been utilized as key steps of total syntheses as exemplified in eq 15. ... 

DMP with high purity by the original procedure therefore, a few modifications have been suggested. In addition, DMP has been successfully used in the syntheses of polycyclic heterocyclesand in the removal of thioketals and thioacetals. It should be mentioned that other hypervalent iodine compounds can be used as oxidants as well, especially for the o-iodoxybenzoic acid (IBX), the precursor to DMP, which can oxidize tertiary cyclic allyl alcohol into O, y0-unsaturated cyclic ketones and secondary amines into imines and can convert epoxides or aziridines into corresponding of-hydroxy ketones or Q -amino ketones. 

Acetal Acetamide Acetone sodium bisulfite Acetophenone Aconitic acid Acrylonitrile Adipamide Alcohol Alloxan monohydrate Allyl amine Allyl anthranilate 2-Aminobenzene sulfonic acid 4-Amino-4 -hydroxy-3-methyldiphenylamine Aminomethyl propanediol Aminomethyl propanol Ammonium hydroxide Arachidic acid Arsine Azelaic acid Benzil... 

---