137664-49-4

Upstream product

• 17342-08-4 (S)-Pyroglutaminol 

Downstream Products

• 137664-64-3 [(R)-1-((4R,5R)-5-{(R)-3-[4-(tert-Butyl-diphenyl-silanyloxymethyl)-oxazol-2-yl]-butylcarbamoyl}-2,2-dimethyl-[1,3]dioxolan-4-yl)-2-methoxy-ethyl]-carbamic acid tert-butyl ester 
• 138253-28-8 [(R)-1-((4R,5R)-5-Benzylcarbamoyl-2,2-dimethyl-[1,3]dioxolan-4-yl)-2-methoxy-ethyl]-carbamic acid tert-butyl ester 
• 138253-29-9 (4R,5R)-5-((R)-1-Dimethylamino-2-methoxy-ethyl)-2,2-dimethyl-[1,3]dioxolane-4-carboxylic acid benzylamide 

Relevant academic research and scientific papers

Total synthesis of (+)-calyculin A and (-)-calyculin B: Cyanotetraene construction, asymmetric synthesis of the C(26-37) oxazole, fragment assembly, and final elaboration

A convergent total synthesis leading to (+)-calyculin A and (-)-calyculin B (1 and 2), antipodes of the potent, highly selective and remarkably cell-permeable phosphatase inhibitors calyculins A and B, has been achieved. In the preceding paper we outlined the asymmetric synthesis of the C(9-25) spiroketal dipropionate subunit (+)-BC; herein we describe construction of the C(1-8) cyanotetraene, an asymmetric synthesis of the C(26-37) oxazole, fragment assembly and final elaboration to (+)-1 and (-)-2. Highlights of the synthesis include: application of a one-pot three-component Suzuki reaction for the construction of phosphonate A, a bifunctional triene precursor of the light sensitive C(1-8) cyanotetraene subunit, an asymmetric synthesis of the C(26-32) oxazole (-)-D, exploiting the Silks-Odom 77Se NMR protocol to assess enantiomeric purity, construction of the C(33-37) subtarget (-)-E in a highly stereocontrolled fashion via an acyliminium ion, and a concise, highly efficient sequence for fragment assembly and elaboration to (+)-calyculin A and (-)-calyculin B. The synthesis of (-)-2 also confirms the structure of calyculin B, previously based only on spectral comparison with calyculin A.

Synthesis of (3R,4R,5R)-1-(tert-butoxycarbonyl)-3,4-isopropylidenedioxy-5-methoxyme thyl-2-pyrrolidinone from (S)-pyroglutaminol

(3R,4R,5R)-1-(tert-Butoxycarbonyl)-3,4-isopropylidenedioxy-5-methoxyme thyl-2-pyrrolidinone (6), a useful chiral intermediate for the preparation of calyculins, was synthesized starting from (S)-pyroglutaminol via the O-methylation of 1c with diazomethane in the presence of fluoboric acid and cis-dihydroxylation of the α,β-unsaturated lactam (4) as the key reactions.

Stereoselective Synthesis of 2,3-Dihydroxy-4-dimethylamino-5-methoxypentanoic Acid, A Fragment of Calyculins - Determination of the Absolute Configuration of Calyculins

2,3-Dihydroxy-4-dimethylamino-5-methoxypentanoic acid (2) with (2R,3R,4R)-configuration has been stereoselectively prepared from (S)-pyroglutaminol (3) and revealed to be the enantiomer of the compound derived from calyculins (1), which provides the conclusicve evidence on the absolutr configuration of calyculins.