H-1 AND C-13 NMR-SPECTRA AND ONE-BOND C-13, C-13 COUPLING-CONSTANTS OF (E)-2-ALKEN-4-YN-1-OLS, (E)-2-ALKEN-4-YN-1-YL ACETATES AND (E)-2-ALKEN-4-YN-1-ALS

C-13 and some selected H-1 NMR chemical shifts of conjugated (E)-enzym es of the type of (E)-2-alken-4-yn-1-ols (RC drop CCH double bond CHCH 2OH; R=H, Me, Et, n-Pr, n-Bu, SiMe3), (E)-2-alken-4-yn-1-yl acetates ( RC drop CCH double bond CHCH2OAc; R=H, Me, Et, n-Pr, n-Bu) and (E)-2-a lken-4-yn-1-als (RC drop CCH double bond CHCH double bond O; R=Et, n-P r) and of (2Z,4E)-deca-2,4-dien-6-yne as a conjugated (Z,E)-dienyne we re measured. The unequivocal assignment of the C-13 NMR chemical shift s is based on the application of standard techniques such as H,H-COSY, C,H-COSY and APT and, above all, on the investigation of the C,C conn ectivities by determination of the one-bond C-13,C-13 coupling constan ts (1)J(C,C). These coupling constants show typical values for the dif ferent structural fragments. The effect of increments of the alkyl gro up on the resonances of the acetylenic carbon atoms are compared with those of the n-alkynes. The shift effects observed on going from (E)-2 -alken-4-yn-1-ols to (E)-2-alken-4-yn-1-als are discussed in compariso n with results from other classes of compounds. (C) 1997 John Wiley & Sons, Ltd.