Trauner synthesis, amathaspiramide

Nitroalkanes have also been reduced to oximes with mixtures of SnCh O, PhSH, and Et3N. 11 As shown below, these conditions were used to achieve the transformation of 25 to 26 in 85% yield. The oxime products of these reactions can be converted to ketones under mild conditions via hydrolysis or oxidation. This method was employed in a key step of Trauner s recent synthesis of (-)-amathaspiramide F (see Section 7.7.6).12... 

Because of their unique structures and skeleton, various groups have targeted to synthesize amathaspiramides. First total synthesis of (-)-amathaspiramide F (134) was reported by Hughes and Trauner, and it is depicted in Scheme 12 [63]. The synthesis was started by taking AA -acetal 136, which was synthesized from L-proline 135. 

Since the isolation of the amathaspiramides in 1999, there have been efforts by various groups toward their total synthesis. In 2002, Trauner reported the first synthesis of a member of this alkaloid family, (—)-amathaspiramide F. The Sakaguchi group followed in 2008 with their own completed synthesis of (—)-amathaspiramide F. It was not until 2012 that other members of the amathaspiramide family were synthesized. The Fukuyama group completed the syntheses of the entire family (amathaspiramides A-F). ... 

Since o-proline was expensive, the Trauner group chose to use L-proline for the synthesis of enf-amathaspiramide F (Scheme 3). The hthium enolate of A(,A(-acetal 2 was difficult to form, and it was ultimately determined that HMPA was required for successful deprotonation. Unfortunately, the conjugated addition to nitrostyrene with the lithium enolate did not provide any... 

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