443283-29-2Relevant academic research and scientific papers
Stereoselective synthesis of E,Z-configured 1,3-dienes by ring-closing metathesis. Application to the total synthesis of lactimidomycin
Gallenkamp, Daniel,Fuerstner, Alois
, p. 9232 - 9235 (2011/08/06)
Strategic positioning of a silyl group on the diene unit of a diene-ene substrate allows rigorous regio- and stereocontrol to be exerted during metathesis-based macrocyclization reactions. The versatility of this concise approach to E,Z-configured 1,3-die
Total syntheses of (+)-tedanolide and (+)-13-deoxytedanolide
Dunetz, Joshua R.,Julian, Lisa D.,Newcom, Jason S.,Roush, William R.
supporting information; scheme or table, p. 16407 - 16416 (2009/05/08)
Convergent total syntheses of the potent cytotoxins (+)-tedanolide (1) and (+)-13-deoxytedanolide (2) are described. The carbon framework of these compounds was assembled via a stereoselective aldol reaction that unifies the C(1)-C(12) ketone fragment 5 with a C(13)-C(23) aldehyde fragment 6 (for 13-deoxytedanolide) or 52 (for tedanolide). Multiple obstacles were encountered en route to (+)-1 and (+)-2 that required very careful selection and orchestration of the stereochemistry and functionality of key intermediates. Chief among these issues was the remarkable stability and lack of reactivity of hemiketals 33b and 34 that prevented the tedanolide synthesis from being completed from aldol 4. Key to the successful completion of the tedanolide synthesis was the observation that the 13-deoxy hemiketal 36 could be oxidized to C(11, 15)-diketone 38 en route to 13-deoxytedanolide. This led to the decision to pursue the tedanolide synthesis via C(15)-(S)-epimers, since this stereochemical change would destabilize the hemiketal that plagued the attempted synthesis of tedanolide via C(15)-(R) intermediates. However, use of C(15)-(S)-configured intermediates required that the side-chain epoxide be introduced very late in the synthesis, owing to the ease with which the C(15)-(S)-OH cyclized onto the epoxide of intermediate 50.
Studies on the synthesis of bafilomycin A1: Stereochemical aspects of the fragment assembly aldol reaction for construction of the C(13)-C(25) segment
Roush, William R.,Bannister, Thomas D.,Wendt, Michael D.,Jablonowski, Jill A.,Scheidt, Karl A.
, p. 4275 - 4283 (2007/10/03)
Highly stereoselective syntheses of aldols 8a-c corresponding to the C(13)-C(25) segment of bafilomycin A1 were developed by routes involving fragment assembly aldol reactions of chiral aldehyde 6a and the chiral methyl ketones 7. A remote chelation effect plays a critical role in determining the stereoselectivity of the key aldol coupling of 6a and the lithium enolate of 7b. The protecting group for C(23)-OH of the chiral aldehyde fragment also influences the selectivity of the lithium enolate aldol reaction. In contrast, the aldol reaction of 6a and the chlorotitanium enolates of 7a,c were much less sensitive to the nature of the C(15)-hydroxyl protecting group. Studies of the reactions of chiral aldehydes with Takai's (y-methoxyallyl)chromium reagent 40 are also described. The stereoselectivity of these reactions is also highly dependent on the protecting groups and stereochemistry of the chiral aldehyde substrates.
Studies on the Synthesis of Tedanolide. 2. Stereoselective Synthesis of a Protected C(1)-C(12) Fragment
Roush, William R.,Newcom, Jason S.
, p. 4739 - 4742 (2007/10/03)
(Matrix Presented) Highly diastereoselective syntheses of diketo esters 6a and 6b are described. These intermediates undergo efficient aldol reactions with protected C(13)-C(21) aldehydes 3 and 23, thereby providing advanced C(1)-C(21) tedanolide seco ester precursors 9a and 9b.
Stereoselective Synthesis of the C(13)-C(25) Segment of Bafilomycin A1
Roush, William R.,Bannister, Thomas D.
, p. 3587 - 3590 (2007/10/02)
The aldol reaction of 2 and the lithium enolate of 3 provides the bafilomycin C(13)-C(25) fragment 1 with 8:1 stereoselectivity.
