Deuterium sodium borodeuteride

Thus, the reduction of tosylhydrazones with sodium borodeuteride in dioxane provides only monodeuterated analogs. For the insertion of two deuteriums it is necessary to first exchange the hydrazone proton and to carry out the reduction in aprotic or deuterated solvents. Under these conditions the reduction of the tosylhydrazone derivatives of 7- and 20-keto... 

Deuterioboration is one of the most important recent additions to the array of methods for saturating double bonds with deuterium. The easy accessibility of metal deuterides (lithium aluminum deuteride or sodium borodeuteride) facilitates the in situ preparation of deuteriodiborane which reacts with steroidal double bonds with a high degree of site and/or stereospecificity, depending on the location of the double bond. " ... 

Still has also carried out mechanistic experiments9 3 from which he could deduce that the major reduction pathway is by attack of hydride ion at the sulphur atom. This conclusion was deduced from the fact that reduction with sodium borodeuteride-aluminium oxide gave a sulphoxide that had only incorporated about 25% mole equivalent of deuterium on to a methyl carbon atom bound to the sulphur atom. The mechanistic pathway for direct reduction is outlined in equation (38), whereas the pathway whereby deuterium could be incorporated is portrayed in equation (39). These reactions support the proposed mechanism for the hydride reduction of sulphones as outlined in Section III.A.l, namely that attack at sulphur by hydride ions may occur, but will be competitive with proton abstraction in cases when the attack at sulphur is not facilitated. 

Eujen and coworkers6-8 prepared trifluoromethylgermane-d3 for an infrared and Raman study, by treating trifluoromethyltriiodogermane with sodium borodeuteride in a phosphoric acid-d3-deuterium oxide mixture at room temperature (equation 7). 

D-(l-2H)Glucopyranose was prepared (170) by direct reduction of D-glu-cono-1,5-lactone, in deuterium oxide solution, with sodium amalgam in the presence of phosphoric acid-rf3, or, alternatively, by reduction of the lactone tetrahydropyranyl derivative with sodium borodeuteride in tetrahydrofuran (171). 

Figure 5. Proposed structure of peak 9 in Figure 4 and its fragmentation pattern. Deuterium at C-l position was introduced during the reduction step with sodium borodeuteride.

SAMPLE SOLUTION (a) Sodium borodeuteride transfers deuterium to the carbonyl group of acetaldehyde, forming a C—D bond. 

Application of alumina-supported sodium borodeuteride under the reaction conditions described by Varma26 provided deuterated alcohols from aldehydes and ketones with a high degree of deuterium incorporation. The method is thus suitable for isotopic labelling procedures (Scheme 4.12)32. 

The reaction course of the reductive photocyclization of enamides in Scheme 17 was firmly established by the experiments using deuterated reagents (75). When enamide 14 was irradiated in the presence of sodium borodeuteride in acetonitrile-methanol (10 1) solution, the isolated product 15 in 93% yield was deuterated at the 3 position, whereas irradiation in the presence of sodium borohydride in acetonitrile-deuterium methoxide solution afforded lactam 16, deuterated in the benzene ring as shown in Scheme 18 (55). 

The main limitation of the use of partially methylated alditol acetates for the characterization of methylated sugars lies in the structural symmetry that may exist when the primary hydroxyl group (0-5 in pentoses and 0-6 in hexoses) is not etherified. This difficulty, however, can be overcome by introducing deuterium at C-1 by reduction of the sugar with sodium borodeuteride. 

Sodium amalgam reduction of organomercurials in alkaline deuterium oxide gives products with stereospecific retention during the replacement of mercury by deuterium [71]. This was shown in the reduction of cw-8-acetoxymercuri- (Ila) and c75-8-chloromer-curidibenzobicylo[2.2.2]octadien-7-ol acetates (Ilb), /ra/75-8-chloromercuridibenzobicy-clo[2.2.2]octadien-7-ol, and some norbornyl derivatives. Reduction of these compounds with sodium borodeuteride gave products without stereospecific deuterium incorporation [71]. 

In 1969 Wiesner and Inaba (65) reported an unusual photoreduction of the C-7-C-17 bond in 16-demethoxylpyrodelphonine (34) to compound 35 by sodium borohydride in methanol. They also repeated the same reaction using sodium borodeuteride to confirm the postulated nature of the pyrochromophore. The high-resolution mass spectrum of the reaction product indicated that one deuterium was incorporated in the reaction product. This result suggested that one of the new hydrogen atoms in compound 35 came from the reagent and the other from the solvent. These results confirm the postulated nature of the pyro chromophore. 

Reduction of (14b) with sodium borodeuteride in 0-deuterio- or 0-deuterioiso-propyl alcohol led to a 97 % monodeuteriated rearranged product in which 80% of the deuterium was incorporated at position 18. 

In agreement with this mechanism, reduction with sodium borodeuteride in AcOH or AcOD results in the regioselective introduction of one or two deuterium atoms, respectively. In deuterated acetic acid, exchange of the N—H proton must be faster than reduction and hydride transfer to carbon (2.42). 

The reaction mechanism for this reductive photocyclization was established as follows. When the enamide was irradiated in the presence of sodium borodeuteride in place of hydride, of course, in acetonitrile-methanol, the product was deuterated at the ring junction as expected, while the photocyclized lactam, when irradiated in the presence of hydride but in acetonitrile and deuterium methoxide, was deuterated at the benzene ring as shown. Thus, the reaction mechanism of this reductive photocyclization was firmly established by the structure in the parenthesis. 

Sinee it is known that sodium borohydride slowly reacts with water to develop hydrogen, and it is commercially available also in deuteride form, we first planned to try the reduction of methyl (5)-dimorphecolate by producing molecular deuterium "in situ from NaBD4 and D2O (NaBD4 + 2 D2O NaB02 + 4D2). Furthermore, sodium borodeuteride is a solid compound, safely stored and available in a powder form that allow quick production of small predetermined amounts of deuterium (D2). However, it should be kept in mind that sodium borohydride itself and its reaction with water are not completely harmless and the reaction must be carried out with the appropriate precautions. 

Oxymercuration is synthetically useful because the reagent sodium borohydride (Na BH4) efficiently replaces the mercury with hydrogen. Figure 10.23 shows the reaction with sodium borohydride and sodium borodeuteride (Na BD4). The use of the deuterated molecule allows us to see with certainty the position of the entering deuterium. 

---