(S)-2-chloro-2-fluoroethanoyl isocyanate, a chiral derivative of trichloroacetyl isocyanate

• Published in: Chirality (New York, N.Y.) Vol. 15; no. 5; pp. 472 - 478
• Main Authors: Vodička, Petr, Streinz, Ludvík, Koutek, Bohumír, Buděšínský, Miloš, Ondrácek, Jan, Císařová, Ivana
• Format: Journal Article
• Language: English
• Published: New York Wiley Subscription Services, Inc., A Wiley Company 2003
• Subjects: acylisocyanate; alcohols; chiral analysis; derivatization; NMR; TAI; trichloracetyl isocyanate
• ISSN: 0899-0042; 1520-636X
• DOI: 10.1002/chir.10231

Carbamate diastereomers 3b–18b were prepared from easily accessible (S)‐2‐chloro‐2‐fluoroethanoyl isocyanate (1) and various secondary chiral alcohols. Compound 1 as a chiral analog of trichloroacetyl isocyanate undergoes the reaction with alcohols very fast, thus blocking the hydroxyl group for the purposes of NMR investigation. Moreover, the correlation of stereochemistry of 3b–18b with their 1H NMR spectra revealed that the constitution as well as configuration influences regularly the values of chemical shift difference (Δδ = δ(R) – δ(S)) except for those diastereomers bearing simple alkyl groups in the molecule. Spectral as well as crystallographic data manifest the predominant planar conformation of the central part of the molecule. Due to the good accessibility and high reactivity in particular, the acylisocyanate 1 might be considered, to some extent, an alternative for TAI giving additional information on a compound's spatial structure. Chirality 15:472–478, 2003. © 2003 Wiley‐Liss, Inc.