Scheme 1. Synthesis of (AB)10 DEACM protected target molecules 8, 13 and their conversion into reference compounds 9, 14, 2, and 3. (A) (a) (ipr2N)P(AB)2, ETT, DMF, then mCPBA; (b) DBU, BSTFA, MeCN then TFA, MeOH, then (ipr2N)P(Fm)(DEACM), then mCPBA; (c) piperidine (1.2 eq.), DMF; (d) chemically: 33% piperidine in DMF; or enzymatically: with MIN6 cell extract; (e) hν; (B) (a) (ipr2N)P(AB)2, ETT, DMF, then mCPBA; (b) DBU, BSTFA, MeCN then TFA, MeOH, then (ipr2N)P(Fm)(DEACM), then mCPBA; (c) piperidine, DMF; (d) chemically: 33% piperidine in DMF; or enzymatically: with MIN6 cell extract; (e) hν; (C) structures of the protecting groups. Abbreviations: ETT 5-ethylthio tetrazole, DMF N,N-dimethylformamide, mCPBA meta-chloroperoxybenzoic acid, DBU 1,8-diazabicyclo[5.4.0]undec-7-ene, BSTFA N,O-bis(trimethylsilyl)trifluoroacetamide, TFA trifluoroacetic acid.
